Is the United States (Still) at War? How Wars Begin and End

During the hostilities with both Venezuela and Iran, the messaging from the Trump administration on their status as an armed conflict has been garbled at best. Under the law of armed conflict (LOAC, also known as international humanitarian law), there are two types of conflicts. An “international armed conflict†(IAC) involves hostilities between States, whereas a “non-international armed conflict†(NIAC) is one between a State and one or more non-State organized armed groups (or between such groups). The question is: where do we stand on that front with the two conflicts?

Regarding Venezuela, the administration (falsely) characterized the drug boat strikes that had begun the prior September as occurring during a NIAC. And then, when the United States attacked Venezuela to seize President Nicolás Maduro and his wife, the administration seemed to treat the operation as solely a law enforcement matter, rather than an armed conflict. As will be explained, both assertions were legally flawed.

The Trump administration has delivered a master class in contradictory messaging about the conflict with Iran. For instance, in March, President Donald Trump claimed, “We've won†(adding, “Nobody else could have done this but me, and you know thatâ€), while on May 2, he notified Congress that “[t]he hostilities that began on February 28, 2026, have terminated.†Three days later, Secretary of State Marco Rubio asserted that Operation Epic Fury “is over.†Regarding the U.S. blockade, he claimed (falsely), “That's not an act of war; that's a defensive measure.â€Â 

Yet, on April 21, the State Department Legal Adviser Reed Rubinstein had issued a statement explaining that “Epic Fury is only the latest round of an ongoing international armed conflict with Iran.†The facts on the ground this month support characterization as a continuing armed conflict. Indeed, the day before Rubio's statement, the U.S. Central Command (CENTCOM) Commander announced that “[t]he IRGC has launched multiple cruise missiles, drones and small boats at announced ships that we are protecting. We have defeated each and every one of those threats through the clinical application of defensive munitions.â€Â 

Then, on May 6, CENTCOM released a statement to the press noting, “U.S. forces disabled a tanker's rudder by firing several rounds from the 20mm cannon gun of a U.S. Navy F/A-18 Super Hornet†after the Iranian-flagged vessel failed to “comply with repeated warnings†to terminate its transit to Iran. The next day, CENTCOM described an engagement in which “Iranian forces launched multiple missiles, drones and small boats†against three U.S. warships transiting the Strait of Hormuz. In response, CENTCOM “eliminated inbound threats and targeted Iranian military facilities responsible for attacking U.S. forces, including missile and drone launch sites, command and control locations, and intelligence, surveillance, and reconnaissance nodes.†Trump labeled Iran's actions “a trifle†and bragged, “We blew them away.†Nevertheless, he claimed the ceasefire was still in place, warning that if it were not, there would be “one big glow coming out of Iran.†The following day, F/A-18s disabled two more Iranian-flagged vessels. 

To clear some of the fog of law, I step back in this explainer to consider three foundational questions: 1) when does war (“armed conflict†in legal parlance) begin, 2) how can it be suspended, and 3) when is it over? (For an extended treatment, see Milanovic, IRRC and Dinstein, ILS.) These are “choice of law†issues, because if armed conflict is underway, LOAC (and in limited circumstances during IACs, the law of neutrality) governs the associated operations. While other bodies of law can continue to operate alongside LOAC, the threshold choice of law question is crucial; it will determine important issues like whether detention or targeting people with lethal force based on their status alone (i.e., as combatants) is permitted. 

This discussion addresses both IACs and NIACs, but not related U.S. constitutional and statutory law issues. Two looming questions in this regard are whether the administration is in compliance with the War Powers Resolution and with the constitutional separation of powers between the President and Congress, issues examined insightfully in other Just Security contributions (see here, here, here, and here). It is also important to emphasize that whether a State's actions have initiated an armed conflict has no bearing on the separate question of whether those actions (or reactions) are lawful under the law governing the resort to force (jus ad bellum). For instance, the first use of force against another State may constitute aggression (unlawful) or anticipatory self-defense (lawful); in either case, an IAC is underway. The lawfulness of the U.S. decisions to resort to force against Venezuela and Iran has been examined in numerous other Just Security articles (collected here and here).

When Does Armed Conflict Commence?

International Armed Conflict: When an IAC begins is the most straightforward of the three questions. The touchstone for the initiation of an IAC is articulated in treaty law – Common Article 2 to the 1949 Geneva Conventions. Although the provision concerns the applicability of those treaties, it is universally accepted as reflecting the points at which an armed conflict between States begins. 

A State's declaration of war, even in the absence of active hostilities, can initiate an IAC. Historically, the 1907 Hague Convention III required that hostilities not commence without prior explicit warning, either through a declaration of war or an ultimatum containing a conditional declaration of war. In contemporary practice, however, formal declarations of war are exceedingly rare. This is because, following World War II, the UN Charter is widely recognized as outlawing war as a legitimate act of State in the absence of Security Council authorization or a lawful invocation of self-defense, neither of which is consistent with declaring offensive war.

Instead, the initiation of an armed conflict is typically a question of fact. In this regard, Common Article 2 identifies “any other conflict†and “partial or total occupation†as factual circumstances that trigger an IAC. Regarding occupation territory is occupied when “it is actually placed under the authority of the hostile army†(Regulations annexed to 1907 Hague Convention IV, art. 42). The International Court of Justice has explained that, under customary international law, “A State occupies territory that is not its own when, and to the extent that, it exercises effective control over it†(emphasis added, 2024 Palestinian Territory, ¶ 90; see also Armed Activities, ¶ 172). The paradigmatic contemporary example is Russia's occupation of Ukrainian territory since 2014.

However, the most common way IACs begin is through intentional hostilities between States. As the International Criminal Tribunal for the former Yugoslavia (ICTY) explained in Tadić, “an armed conflict exists whenever there is a resort to armed force between States†(Jurisdiction, ¶ 70). The reference to hostilities between States does not require both sides to use force; rather, it means that one State must be using armed force against another. 

The “between States†condition is also satisfied when an organized armed group, such as a terrorist group, acts under the “overall control†of one State when using force against another State (Tadić, Appeals Judgment, ¶ 131; ICJ, Bosnian Genocide, ¶ 404). Such control must be demonstrated “not only by equipping and financing the group, but also by coordinating or helping in the general planning of its military activity†(Tadić, Appeals Judgment, ¶ 131). Thus, depending on the extent of Iranian involvement in Houthi attacks on U.S. warships, the exchanges between that group and the United States during Operation Rough Rider last year could have amounted to an IAC with Iran. However, based solely on publicly available accounts of that relationship, the better characterization is that, despite Iranian support for the group, the exchanges occurred in the context of an NIAC (see below) between the United States and the group. 

The key issues are the required intensity and the type of action. Regarding the former, the 2025 ICRC Commentary to Geneva Convention IV notes that “[i]t makes no difference how long the conflict lasts, or how much slaughter takes place†(¶ 306). The United States likewise holds that an IAC encompasses “any situation in which there is hostile action between the armed forces of two parties, regardless of the duration, intensity, or scope of the fighting†(DoD Law of War Manual, § 3.4.2). Thus, when a State's organs, such as the armed forces or a paramilitary intelligence organization, “shoot at†another State's forces, an IAC is triggered, even before the other State reacts, if at all. The approach applies equally when force is used against entities, objects, or persons because of their relationship to another State. For instance, if a State attacks a merchant vessel because it is flagged in another State or kills individuals based on their citizenship, the action initiates an IAC with that State. 

The concept of using “force†in the context of initiating an IAC is broad. As noted with respect to occupation, it includes merely crossing into another State's territory and securing control of it (without firing shots). Forcibly detaining one or more members of another State's armed forces also likely triggers an IAC (Commentary, ¶ 309), as does declaring and enforcing a blockade under the law of naval warfare (¶ 293). The logical corollary – that maintaining a blockade is legally possible only in an ongoing armed conflict – renders any U.S. claim that the conflict with Iran has been “terminated†while simultaneously enforcing the blockade internally inconsistent. 

By this standard, the Jan. 3 U.S. use of force against Venezuela during Operation Absolute Resolve to seize the Venezuelan President and his wife, Cilia Flores (both were indicted on narco-terrorism and drug trafficking charges), unambiguously triggered an IAC between those States (see analysis here). The question regarding Venezuela is whether the conflict continues (see below). The same is true of Operation Epic Fury, which commenced on Feb. 28 with attacks against Iranian targets. The ongoing exchange of hostilities between the United States and Iran is sufficient to confirm that the conflict continues today, irrespective of any statements by U.S. officials. Any U.S. assertion that Operation Epic Fury is over is legally meaningless in light of those exchanges. We are “at war†with Iran and will remain so as long as fighting continues, the blockade is underway, or the conflict has not been concluded as described below.

Non-international Armed Conflict: Non-international armed conflicts occur between States and non-State organized armed groups only when two criteria are satisfied – there is a sufficient level of organization of the group, and the intensity of the hostilities reaches a sufficient threshold (Tadić, Jurisdiction, ¶ 70; DoD Law of War Manual, § 17.1.1). The former requires that the group be armed, have a command structure, and possess the organizational capacity to conduct and sustain military operations. It need not be organized in precisely the same manner as traditional military units, but it must be “military-like†(see sample indicia drawn from jurisprudence in the ICRC's 2024 Opinion Paper, pages 13-14). 

As to intensity, the ICTY explained in Tadić that NIACs are characterized by “protracted armed violence†(Jurisdiction, ¶ 70). The critical issue in this regard is less the duration of hostilities than the level of violence. For instance, in Limaj, the ICTY noted that the two criteria are used “solely for the purpose, as a minimum, of distinguishing an armed conflict from banditry, unorganized and short-lived insurrections, or terrorist activities, which are not subject to international humanitarian law†(Tadić, Trial Judgment, ¶ 562; Limaj, Judgment, ¶ 89; see also ICRC Opinion Paper, pages 14-15). Thus, even some deaths or instances of property damage do not suffice. In practice, the level of violence must generally exceed what law enforcement agencies can handle. 

The Trump administration has claimed, in a congressional notification and a statement to the U.N. Security Council, that its attacks on alleged drug boats (Operation Southern Spear) are being conducted in the context of a NIAC with drug cartels. I agree that, in some cases, a State can be involved in a NIAC with a drug cartel, for the motivation for using violence need not be political (see, e.g., Vité, page 78; ICRC GC IV Commentary, ¶ 524). Very violent NIACs with drug cartels have occurred, for example, in both Colombia and Mexico (on organized crime and LOAC, see the IRRC issue on point). As I have explained elsewhere, I am also of the view that a NIAC can transcend borders, even beyond so-called “spill over†areas in neighboring countries, a view that is not shared, for instance, by the ICRC (2024 Opinion Paper, page 18). 

But as Tess Bridgeman, Ryan Goodman, and I have explained before (see here, here, here), the current operations against suspected drug boats do not constitute a NIAC. Some of the groups whose members or affiliates are ostensibly involved may possess weapons and be hierarchically structured. Still, their arms and organization serve criminal purposes, not to engage in hostilities with the United States. In other words, to qualify as an organized armed group, the group, regardless of its foundational motivation (crime, politics, etc.), must be armed and organized to direct violence at the State, as in the case of weakening State control over territory to a degree that facilitates drug activities. Indeed, since Operation Southern Spear began, the targeted groups (some better described as gangs rather than cartels) have shown no significant ability or desire to fight back. 

At least when the United States made the claim as the boat strikes began, the intensity of the hostilities – one-sided, periodic strikes killing only a few people – fell well below the threshold required to initiate an NIAC. It might be argued that the United States has now killed so many members of the cartels that the intensity requirement is satisfied. After all, as of May 11, 193 people aboard the boats have reportedly died in 58 strikes in the Caribbean Sea and the Pacific Ocean. But that argument might be undercut by the fact that, unless acting in concert, the intensity requirement is assessed individually for each group. In any event, groups such as Tren de Aragua and Cartel de los Soles do not constitute organized armed groups under LOAC. The more apt question remains, unfortunately, whether the killings that are unlawful in part because they are taking place outside of armed conflict now rise to the level of crimes against humanity under international human rights law (as has been concluded here and here, and with which I agree). 

What is the Effect of the Suspension of Hostilities?

A lull in fighting does not, of itself, end an armed conflict. Parties to the conflict stop shooting for many reasons without bringing the conflict to a legal close – preparing for an operation, regrouping after a defeat, reorienting forces, pausing for political reasons, or even awaiting changes in the weather. But the parties may also agree to stop fighting through a ceasefire. 

Before turning to the substance, it is important to note that terminology can be confusing. The historical term “armistice†still appears in some sources when referring to what will be labeled a ceasefire here (e.g., DoD Law of War Manual, § 12.11). In contemporary usage, however, “ceasefire†typically denotes a temporary suspension of hostilities, “armistice†typically refers to a permanent cessation short of a peace treaty, and the full restoration of peaceful relations is achieved through a “peace treaty†(see my explanation; Dinstein, War, Aggression and Self-Defence, pages 44-47).

Ceasefires can be agreed to for purposes ranging from observing holidays (e.g., Victory Day in the Ukraine-Russia War) to pausing fighting during negotiations. The legal framework for ceasefires is derived principally from the Regulations Annexed to the 1907 Hague Convention IV, which reflect customary international law binding on all States (ICJ, Nuclear Weapons, ¶ 80, confirming Nuremberg IMT, vol. 1, page 254). Although the Convention applies only to IACs, the principles it expresses apply mutatis mutandis to NIAC ceasefires. 

The Regulations explain that ceasefires “suspend military operations†(art. 36), meaning hostilities against the adversary. They may also impose other requirements, such as a ceasefire monitoring mechanism (see other examples in the DoD Law of War Manual, § 12.12). Ceasefires can be “general†(suspending hostilities everywhere) or “local†(e.g., to allow the evacuation of the wounded under GC I, art. 15). The agreement may set a duration, as with what appears to be a partial ceasefire in the Iran war, which was initially for two weeks. However, if the parties agree, whether explicitly or implicitly, the ceasefire may continue indefinitely, as is the case with the current situation between the United States and Iran (bracketing for the moment the ongoing U.S. naval blockade and a number of possible violations). When a ceasefire is or becomes indefinite, either party may resume hostilities once the adversary's forces have been notified, either in accordance with the ceasefire's terms or with sufficient notice to preclude surprise (Hague Convention IV Regulations, art. 36).

In the event of a serious violation of the ceasefire's terms by one of the parties (a “material breachâ€), the other party may denounce the agreement or, in urgent situations, immediately recommence hostilities (art. 40; DoD Law of War Manual, § 12.13.1). Importantly, the aggrieved party need not exercise this right. As a matter of law, both the United States and Iran appear to have committed material breaches in this ceasefire period; each has accused the other of doing so. However, because neither side has denounced the agreement or resumed comprehensive hostilities, the ceasefire remains in effect. 

The takeaway for the current conflict is that the ceasefire, as explained in DoD's Law of War Manual (§ 12.11.1.2), 

is not a partial or a temporary peace; it is only the suspension of military operations to the extent agreed upon by the parties to the conflict. War as a legal state of hostilities between parties may continue, despite the conclusion of an armistice agreement.

When is the Armed Conflict Over?

For both IAC and NIAC, conflict termination can be more difficult to discern and requires a careful examination of the facts. Some situations clearly reflect the termination of armed conflict, while others are more ambiguous or contested, as explained below. 

International Armed Conflict: International armed conflicts may end through a peace treaty or a treaty that formally terminates hostilities without restoring peace between the belligerents (see my explanation here). As noted, the latter are most commonly labeled “armistices†today, as in the armistice that ended the First World War on Nov. 11, 1918, preceding the restoration of the belligerents' peaceful relations with Germany in the 1919 Treaty of Versailles. Both types of instruments must be executed on behalf of the States concerned, meaning that, unlike ceasefires, operational commanders have no authority to execute them on their own. They must be general in character and permanent; accordingly, the parties lose the right to resume hostilities altogether (a jus ad bellum issue). If hostilities break out after the execution of an armistice, a new IAC will have been initiated. In the current context, it must also be emphasized that a unilateral declaration that an armed conflict has been terminated – as Trump's May 2 letter to Congress might be read to mean – does not, without more, have that effect.

An armed conflict can also end through the complete subjugation of the enemy (debellatio). However, this category is exceptional in modern law. It must be understood against the backdrop of the UN Charter prohibition on the acquisition of territory by force in Article 2(4) and the law of occupation, and the rules of necessity and proportionality that are customary jus ad bellum rules binding on all States. 

In contemporary warfare, an IAC most commonly ends as a matter of fact and law, rather than by agreement. This occurs upon the “general close of military operations.†The term first appeared in Article 6(2) of the 1949 Geneva Convention IV. It was subsequently included in Article 3(b) of the 1977 Additional Protocol I, which applies not only to that instrument but also to all four 1949 Geneva Conventions

The ICRC's 2025 Geneva Convention IV Commentary to Common Article 2 explains that “evidence that there has been a ‘general close of military operations' is the only objective criterion to determine that an international armed conflict has ended in a general, definitive and effective way†(¶ 347; see also ICTY, Gotovina, ¶ 1694; Tadić, ¶ 70). According to the ICRC, “‘[m]ilitary operations' means the movements, manoeuvers and actions of any sort, carried out by the armed forces with a view to combat†(AP I Commentary, ¶ 152). In this regard, the Commentary explains, “[m]ilitary operations short of active hostilities pitting one belligerent against another would still justify per se the continued existence of an international armed conflict provided one can reasonably consider that the hostilities between the opposing States are likely to resume in the near future owing to their ongoing military movements†(¶ 350). The DoD Law of War Manual is in accord: 

It may be difficult to determine when an armed conflict has ceased, as opposed, for example, to a lull in hostilities during which opposing forces may simply be reconstituting themselves. Hostilities generally would not be deemed to have ceased without an agreement, unless the conditions clearly indicate that they are not to be resumed or there has been a lapse of time indicating the improbability of resumption (§ 3.8.1.2).

This is a high bar that goes beyond the “cessation of active hostilities,†the point at which prisoners of war are to be released and repatriated (GC III, art. 118). Fighting may have stopped, but until the attendant facts demonstrate that the parties intend the cessation to be permanent and that the situation is stable, the IAC and the applicability of the LOAC continue. The objective factual situation, not political pronouncements, is the controlling criterion.

The “general close of military operations†has been achieved in the IAC between Venezuela and the United States. Active hostilities ceased almost immediately after Maduro was captured, and U.S. forces withdrew from Venezuelan territory. Naval operations, including interdiction of Venezuelan oil tankers, continued for a time, alongside threats of the resumption of other combat operations, creating some lingering ambiguity as to whether the conflict had in fact terminated. Even today, maritime forces remain in the area, though they are now there primarily to conduct Operation Southern Spear strikes. Importantly, relations have generally normalized. In March, the U.S. Embassy in Caracas reopened, and the United States and Venezuela agreed to reestablish diplomatic and consular relations. No exchange of fire has occurred since then, and no military mobilization motivated by a potential return of hostilities has taken place. Simply put, the resumption of hostilities appears highly unlikely. 

Regarding Iran, it bears noting that an IAC between that country and the United States was triggered in June 2025 when Israel (Operation Rising Lion) and the United States (Operation Midnight Hammer) attacked (see the Just Security collection). In its April legal analysis of the current hostilities, the State Department argued that “the facts clearly support the proposition that the international armed conflict involving Iran, Israel, and the United States that was the subject of the June 27 Article 51 letter is ongoing.†Adopting the “general close of military operations†standard, it explained, 

There is no evidence that any of the parties—Iran, Israel, or the United States—intended or decided to end [the Israel-Iran or the United States-Iran IACs] after the June 2025 operations. The parties did not make unilateral declarations concerning an end to hostilities, nor did they conclude any agreement related to the end of hostilities. After the June 2025 strikes, the parties observed a ceasefire to allow diplomatic negotiations to address the Islamic Republic's continuing threat to the United States, Israel, and the region, but those negotiations failed. As was widely reported in the media, all parties—including Iran—continued to actively plan for further military engagements if diplomacy failed. The pause in hostilities during this period thus lacked the “stability†and “permanence†that must, as a matter of international law, be present to indicate an end to hostilities.

This is, in my view, a fair reading of the law governing termination of IACs, although Trump's statement following Operation Midnight Hammer of “an Official END to THE 12 DAY WAR†would point in the other direction. Still, I am persuaded, with the benefit of hindsight, that when the United States attacked Iran on Feb. 28 of this year, it did so in the context of an IAC that had been ongoing since at least last June. Given that there is now a fragile ceasefire designed to facilitate negotiations, that ceasefires are temporary, and that exchanges of fire between the two sides continue, it is incontestable that the international armed conflict is still underway today.

Non-international Armed Conflict: As explained above, there was no non-international armed conflict with the groups targeted in Operation Southern Spear; nor is there one now, for the same reasons. However, for the sake of completeness, a brief mention of how NIACs end is merited. 

Although there is no treaty law directly on point, the ICRC's 2025 Commentary on Article 3 of Geneva Convention IV provides a sound discussion of the matter. It notes that the determination is “purely fact-based†(¶ 561). Adopting much the same approach as applies to IACs, the Commentary explains that “a lasting cessation of armed confrontations without real risk of resumption will undoubtedly constitute the end of a non-international armed conflict as it would equate to a peaceful settlement of the conflict, even without the conclusion or unilateral pronouncement of a formal act such as a ceasefire, armistice or peace agreement†(¶ 565). 

Importantly, the fact that the violence subsequently falls below the intensity threshold required for initiation of a NIAC is not necessarily dispositive, since hostilities may resume at the requisite level in the future. NIACs may persist through such ebbs and flows, for, as noted in the Commentary,

The classification of a conflict must not be a “revolving door between applicability and non-applicability†of international humanitarian law, as this can “lead[] to a considerable degree of legal uncertainty and confusionâ€. An assessment based on the factual circumstances therefore needs to take into account the often-fluctuating nature of conflicts to avoid prematurely concluding that a non-international armed conflict has come to an end. (¶ 567, citing Gotovina, ¶ 1694). 

Nevertheless, the Commentary observes, “the lasting absence of armed confrontations between the original Parties to the conflict may indicate – depending on the prevailing facts – the end of that non-international armed conflict, even though there might still be minor isolated or sporadic acts of violence†(¶ 568). In other words, a NIAC ends when one party prevails definitively or when there is no longer any reasonable likelihood that the violence will reach the requisite threshold again.

Concluding Thoughts

The legal point is straightforward, even if the administration's messaging is not. Armed conflict is not a matter of political branding, rhetorical convenience, or domestic law positioning. It is a legal status that turns on objective facts and legal criteria. That matters because legal classification determines the applicable law; LOAC and, in international armed conflicts, the law of neutrality apply only when the relevant thresholds are met. 

Nor can armed conflict be wished away. It does not disappear because a president declares it has ended, because an operation is rebranded or renamed, or because fighting pauses while negotiations proceed. Political messaging may cloud the issue, but it cannot alter the law. With Venezuela, the United States was briefly at war; with drug cartels and gangs in Latin America, the United States was not and never has been; and with Iran, the United States still is.

FEATURED IMAGE: In this handout photo provided by U.S. Central Command, Arleigh Burke-class guided-missile destroyer USS Rafael Peralta (DDG 115) implements a maritime blockade against an Iranian-flagged ship attempting to sail toward an Iranian port, on April 26, 2026 in the Arabian Sea. Rafael Peralta is deployed to the U.S. 5th Fleet area of operations to support maritime security and stability in the Middle East. (Handout photo by U.S. Navy via Getty Images)