US Escalation in Iran: Can the United States Legally Strike Iran?

Quick summary: As of mid-July 2026, the United States and Iran are locked in a fast-moving cycle of strikes and counter-strikes despite a memorandum of understanding signed in mid-June that was meant to end their war. President Trump has ordered several rounds of attacks on Iranian military, naval, and air-defense targets in response to Iranian strikes on commercial shipping in the Strait of Hormuz, and Iran has retaliated against U.S. bases across the Gulf. Under U.S. law, the President has claimed independent constitutional authority as Commander-in-Chief, while Congress has passed (non-binding and vetoed) war powers resolutions arguing the conflict is unauthorized. Under international law, the U.S. justification rests on collective and individual self-defense under Article 51 of the UN Charter, a claim that legal scholars and several UN member states dispute. This article breaks down what's actually happening, what the law says, and where things go from here.

What's Actually Happening Right Now

The current round of fighting traces back to February 28, 2026, when the United States and Israel launched joint strikes on Iran that killed Iran's Supreme Leader, Ali Khamenei, in the opening hours of the conflict. After weeks of combat, President Trump ordered a ceasefire on April 7, 2026, and the two sides signed a memorandum of understanding (MoU) in mid-June, opening a 60-day window for peace negotiations.

That truce didn't hold. In late June, Iran attacked commercial vessels for using what it called an "unauthorized route" near the Strait of Hormuz, and the U.S. responded with strikes along the strait on June 26. From July 7 through at least July 12, the exchanges escalated sharply:

• The U.S. hit more than 80 Iranian targets on July 7–8, then roughly 90 more on July 8–9, and around 140 targets on July 11–12, striking air-defense systems, command-and-control networks, coastal radar, missile and drone storage sites, and Islamic Revolutionary Guard Corps (IRGC) naval assets.
• Iran retaliated with drone and missile strikes on U.S. military installations in Kuwait, Bahrain, Jordan, Qatar, Oman, and the UAE.
• The Treasury Department reimposed sanctions on Iranian oil exports.
• Iran briefly claimed to have closed the Strait of Hormuz to shipping; U.S. Central Command disputed that the strait was actually blocked.
• President Trump told reporters at the NATO summit in Ankara that he considers the MoU "over," though he has also said talks could continue.

So to directly answer the common search questions:

Is the US-Iran war going to escalate? It already has. What began as a ceasefire violation over shipping attacks turned into the most intense exchange of fire since the initial war in February and March 2026. Whether it turns into full-scale renewed war depends on whether backchannel diplomacy, which U.S. officials say is continuing even between rounds of strikes, can hold.

What is the current status between the US and Iran? The two countries are technically still operating under the June memorandum of understanding, but both sides accuse the other of violating it. There is active combat, Gulf allies are urging restraint, and negotiators are reportedly still meeting even as strikes continue.

Has Iran agreed to a deal with the United States? Not a final one. Iran and the U.S. reached an interim ceasefire in April and a memorandum of understanding in June that opened a negotiating window, but no permanent settlement has been reached. Iranian officials have said the renewed strikes make diplomacy "futile," while U.S. officials say Iran has reached out about a new deal even as fighting continues.

Why did the US attack Iran again? U.S. Central Command has said the strikes are retaliation for Iranian attacks on commercial tankers transiting the Strait of Hormuz and are meant to degrade Iran's capacity to threaten shipping in that waterway.

Can the United States Legally Strike Iran? Two Separate Legal Questions

Whether a strike is "legal" actually involves two different legal systems that don't always agree with each other:

1. U.S. domestic law - does the President have the authority to order strikes without a new vote from Congress?
2. International law - does the U.S. have a lawful basis under the UN Charter to use force against another sovereign state?

A strike can be defensible under one framework and contested under the other. That's exactly the situation right now.

The Domestic Law Question: Who Gets to Authorize War?

The U.S. Constitution splits war powers between two branches. Congress holds the power to declare war (Article I), while the President is Commander-in-Chief of the armed forces (Article II). In practice, this split has caused friction in nearly every modern conflict, and Iran is no exception.

The War Powers Resolution. Passed in 1973 over President Nixon's veto, the War Powers Resolution requires the President to notify Congress within 48 hours of introducing forces into hostilities, and it caps unauthorized combat operations at 60 days (with a 30-day withdrawal window) unless Congress declares war or specifically authorizes the action.

What the administration has argued. After the February 28 strikes, the White House submitted a report to Congress citing the President's "constitutional authority as Commander in Chief and Chief Executive to conduct United States foreign relations," rather than seeking specific congressional authorization. When the 60-day clock under the War Powers Resolution approached in May, the administration told Congress that hostilities had "terminated" because of the April 7 ceasefire, an argument that stopped the clock, at least in the executive branch's own accounting.

What Congress has done. Lawmakers have pushed back repeatedly. In late June, the Senate passed a war powers resolution directing the President to remove U.S. forces from hostilities against Iran unless Congress explicitly authorizes further action, a resolution four Republicans crossed party lines to support. The House later passed its own measure aimed at ending the war. Neither has become binding law: the Senate's joint resolution would need the President's signature (and he is expected to veto it), and the administration has dismissed the House measure as an unconstitutional attempt to legislate away executive authority.

Where that leaves things. As of now, there is no congressional declaration of war and no specific statutory authorization for use of military force against Iran, comparable to the authorizations Congress passed for Afghanistan or Iraq. The President is relying on inherent Article II authority, and Congress has expressed disapproval through non-binding and vetoed measures rather than cutting off funding, which legal commentators note is the one tool that would actually have teeth. Courts have historically been reluctant to referee these disputes, generally treating war powers conflicts between Congress and the President as a "political question" better resolved between the two elected branches than by judges.

The International Law Question: Self-Defense Under the UN Charter

Separate from U.S. domestic law, international law governs whether one country can lawfully use force against another. The starting point is Article 2(4) of the UN Charter, which prohibits the use of force against the territorial integrity or political independence of any state. The main exception relevant here is Article 51, which preserves:

"the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken the measures necessary to maintain international peace and security."

Any country invoking this right is required to report the measures it takes to the UN Security Council.

The U.S. justification. The administration's war powers reports have framed the strikes as protecting U.S. forces and the homeland, defending national interests, and acting in "collective self-defense" of regional allies, particularly Israel. For the more recent rounds of strikes tied to the Strait of Hormuz, the legal rationale shifts slightly: these are framed as direct responses to Iranian attacks on commercial vessels and on U.S. bases in Kuwait, Bahrain, and elsewhere, which the U.S. treats as armed attacks triggering a self-defense response.

Why this is legally contested. Article 51 self-defense has three generally recognized limits under customary international law, drawn largely from the International Court of Justice's reasoning in cases like Nicaragua v. United States:

• Necessity - force must be a last resort, used only when non-military options won't stop the attack.
• Proportionality - the response must be limited to what's needed to repel the attack, not open-ended retaliation.
• Imminence or an actual armed attack - self-defense is triggered by an armed attack that has occurred or is clearly about to occur, not a generalized or long-term threat.

Legal scholars and several governments have questioned whether repeated, large-scale strikes on air defense systems, command networks, and dozens of targets across Iran sustained over months fit the proportionality and necessity requirements, or whether they've moved into the territory of an ongoing offensive campaign that self-defense doctrine wasn't designed to justify indefinitely. Iran, for its part, has filed a formal complaint with the UN Security Council and the Secretary-General, calling the strikes a violation of the interim agreement and, in its own statements, invoking its own right of self-defense to justify counterstrikes on U.S. bases in the region.

The UN Secretary-General has repeatedly urged both sides to exercise "maximum restraint" and avoid further escalatory action, and has called for negotiations to continue and for shipping through the Strait of Hormuz to be restored, signaling that the UN's own position is that the situation has moved past what either side can credibly justify as narrow, proportionate self-defense.

So, Is It Legal?

There isn't a single yes-or-no answer, and any source telling you otherwise is oversimplifying:

• Under U.S. domestic law, the strikes are not clearly illegal because the President has statutory and historical room to act unilaterally in the short term, and Congress has not used its strongest tool, the power of the purse, to stop him. But the strikes are also not clearly authorized, since there is no war declaration or specific statutory authorization, and both chambers of Congress have now gone on record disputing the legal basis.
• Under international law, the U.S. has a colorable but contested self-defense argument tied to specific Iranian attacks on shipping and U.S. bases. Whether that argument holds up depends on whether each individual strike is proportionate to the specific attack it's responding to, which is a fact-specific question that international bodies, not domestic commentators, are best positioned to assess over time.

In short: the administration has a legal argument for each individual strike, but the cumulative, months-long pattern of escalation is precisely what makes international lawyers, members of Congress, and UN officials uneasy because self-defense law was built around discrete responses to attacks, not sustained campaigns.

What to Watch Next

• Whether the MoU survives. Both sides have accused the other of violating it, but neither has formally declared it dead, and back-channel talks reportedly continue even during active strikes.
• Congressional funding fights. The Pentagon has sought a large supplemental budget request tied largely to the Iran conflict; how Congress handles that request will be a more meaningful signal of its actual leverage than another non-binding resolution.
• UN Security Council action. Iran's formal complaint puts the dispute before the Security Council, though any binding action would likely face a U.S. veto.
• Strait of Hormuz shipping. Continued attacks or closures there affect global oil markets and increase the odds that other states get pulled into the conflict.

Sources:

• United Nations, Charter of the United Nations, Article 51
• Cornell Law School, Legal Information Institute, 50 U.S. Code § 1541 - War Powers Resolution, Purpose and Policy
• U.S. Government Publishing Office, War Powers Resolution, Public Law 93-148 (full text)
• United Nations Security Council Report, In Hindsight: The Increasing Use of Article 51 of the UN Charter and the Security Council

This article is for informational purposes only and does not constitute legal advice. The situation between the United States and Iran is developing rapidly; readers should confirm the latest status through official government sources before relying on any specific detail.