Geoffrey Corn is a professor of law at Texas Tech University School of Law and a retired U.S. Army lieutenant colonel who served as an intelligence officer and military lawyer. Orde Kittrie is a professor of law at Arizona State University, senior fellow at the Foundation for Defense of Democracies and former lead State Department attorney for nuclear affairs.
The latest U.S. military attacks against Iran have been criticized by several members of Congress — including Sen. Tim Kaine (D-Virginia), Rep. Thomas Massie (R-Kentucky) and Sen. Mark R. Warner (D-Virginia) — who argue the Iranian threat, nuclear or otherwise, was insufficiently imminent to justify self-defense.
Warner condemned President Donald Trump for launching a “war of choice” against Iran. Without releasing classified information, it might be difficult for the administration to rebut criticism relating to the imminence of Iran’s nuclear threat.
There is, however, another more compelling international legal justification: This campaign continues an ongoing and long-term armed conflict with Iran.
Why does this matter? As reflected in Article 51 of the U.N. Charter, all states have a right to act in self-defense in response to an actual or imminent unlawful armed attack. Iran’s assaults against U.S. personnel, bases, ships and Israel, which have been ongoing for at least the past several years, triggered that right, as reflected in the military responses ordered by Trump and President Joe Biden against the regime and its proxies. That U.S. right of self-defense continues until Iran’s willingness or capacity to continue such aggression ends.
International law does not require a distinct self-defense justification for every attack conducted once the right of self-defense is triggered. Once that right is initiated, military action is justified to achieve the overall self-defense objective, in this case terminating Iran’s capacity to strike the United States and its allies.
Some may argue that Iran’s attacks on America and other nations have been a series of distinct events rather than a continuing conflict justifying U.S. military action. This view is illogical and inconsistent with international law. Iran has for years exploited perceived moments of opportunity to launch attacks, directly or through its proxies.
There are strong arguments that the conflict has been ongoing for the 47 years since the Iranian Revolution. Unquestionably, this armed conflict has persisted over the past several years. That the U.S. has historically chosen to tolerate acts of Iranian aggression or respond in limited ways in no way negates the reality of this conflict.
Before the current hostilities, Iran’s most recent actions against the U.S. occurred on Feb. 3, when an Iranian drone “aggressively approached” and was shot down by a U.S. aircraft carrier in the Arabian Sea. Hours later, two gunboats operated by Iran’s Islamic Revolutionary Guard Corps (IRGC) threatened to seize a U.S.-flagged tanker in international waters.
According to a 2024 report by Biden’s Director of National Intelligence, between October 2023 and November 2024, “the Iranian military helped facilitate” at least 190 attacks against U.S. military forces by Iranian-aligned militants. During 2025, the Iranian-backed Houthis repeatedly attacked U.S. naval ships in the Red Sea. Also in 2025, Iranian proxies attacked U.S. personnel in Iraq and Syria.
During the same period, Iran brought its “shadow war” to U.S. soil. The Biden and Trump justice departments have documented Iranian plots to assassinate Trump, former secretary of state Mike Pompeo, former national security adviser John Bolton and Iranian American women’s rights activist Masih Alinejad.
Since the Iranian Revolution in 1979, Iran has been held responsible for the deaths of 603 U.S. troops in Iraq between 2003 and 2011, 241 service members in the 1983 U.S. Marine barracks bombing in Beirut, three soldiers in Jordan in January 2024 and dozens of U.S. civilians.
These facts justify the conclusion that the U.S. and Iran were already engaged in an armed conflict when the current round began. As a result, international law does not require the U.S. to refrain from further military action against Iran until just before the IRGC launches another assault.
Wars do not progress on a flatline of intensity. Instead, it is logical and legally valid for the U.S. to target enemy military sites when and where such strikes are most likely to accomplish objectives and produce maximum advantage. This approach is inherent in the numerous times U.S. presidents and military officials have stated the U.S. will respond to Iranian aggression “at a time and place of our choosing.”
Explaining this bipartisan cornerstone of U.S. policy, Brian J. Egan, while serving as State Department legal adviser under President Barack Obama, said, “In the view of the United States, once a State has lawfully resorted to force in self-defense against a particular armed group following an actual or imminent armed attack by that group, it is not necessary as a matter of international law to reassess whether an armed attack is imminent prior to every subsequent action taken against that group, provided that hostilities have not ended.”
International law does not require the U.S. and its allies to endlessly endure and absorb Iranian aggression. The U.S. military is engaged in decisive action to permanently stop Iranian attacks. America is fighting a war that Iran chose.
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