U.S. Strike Destroys Iran's B1 Bridge, Killing Civilians on Nowruz Holiday

What Happened

On April 2, 2026, United States forces destroyed the B1 bridge near Karaj, approximately 40 kilometers west of Tehran. The B1 was Iran's most ambitious and complex engineering project — an "extradosed" bridge system standing 176 meters high and stretching 1,050 meters long. Wikipedia describes it as unfinished; The War Zone described it as a major transport artery opened earlier in the year. The US military said it was striking a planned military supply route for Iranian missiles and drones.

The bridge was hit in two waves of strikes separated by around an hour, Iranian state TV reported. Families gathered underneath and near the bridge for Sizdah Bedar, the "Day of Nature" that ends Nowruz, when millions of Iranians gather outdoors, were in the area. Iran's Fars News Agency reported that the second strike hit first responders who had arrived to help the wounded; this has not been independently verified, and an hour-long interval is also consistent with a re-attack to complete the bridge's destruction. Alborz provincial governor Ghodratollah Seif said eight people were killed and 95 wounded.

Hours after the strike, President Trump posted on social media: "The biggest bridge in Iran comes tumbling down, never to be used again — Much more to follow!" The message was followed by warnings targeting all of Iran's bridges and power plants (see the civilian infrastructure threats entry).

Iranian Foreign Minister Abbas Araghchi condemned the attack as evidence of the "moral collapse of an enemy in disarray."

The B1 Bridge: Civilian Object or Military Objective?

Iran says the bridge had no military use, and the Alborz governor denies any military activity there. The US military described it as "a planned military supply route for Iranian missiles and drones," and The New York Times reported that it was part of a planned supply route for Iran's ballistic missile and drone forces. A planned or prospective military use can satisfy the "purpose" limb of the military-objective test (Additional Protocol I, Article 52(2)), and major road bridges are classic dual-use objects. No independent body has tested the US claim.

Trump's social media post, and his earlier threats, are evidence of a coercive purpose: a former State Department lawyer, Brian Finucane, suggested the bridge was targeted "in the hopes of coercing Tehran." Rhetoric is evidence of purpose but does not by itself establish the legal elements of a war crime. Benjamin Farley, writing in Foreign Policy, concluded that the Karaj strike "may have been lawful," while treating Trump's threatened blanket destruction of all bridges and power plants as unlawful.

The Second Strike

A "double-tap" strike — bombing the same location twice, with the second strike timed to hit first responders — is one of the most condemned tactics in modern warfare. Iranian media (Fars) report that the second B1 strike, roughly an hour after the first, hit first responders; this has not been independently verified.

If rescuers were present and visible, Additional Protocol I, Article 57 required attackers to take "constant care" to spare civilians and to cancel or suspend an attack that would cause disproportionate civilian harm. Rescuers are civilians and count in the proportionality assessment.

Timing: Nowruz and Sizdah Bedar

The strike occurred on Sizdah Bedar — the thirteenth day of Nowruz, the Iranian New Year. Sizdah Bedar, known as "Nature Day," is one of the most widely observed holidays in Iran. Families spend the day outdoors in parks, by rivers, and under bridges and overpasses — exactly the kind of gathering that was taking place under the B1 bridge when the strikes hit.

The timing raises the question of whether the attackers knew — or should have known — that civilians would be present in the strike area during a national holiday. Under the principle of precaution in attack (Article 57), parties to a conflict are required to do everything feasible to verify that targets are military objectives, to assess whether an attack will cause disproportionate civilian harm, and to choose methods that minimize civilian casualties. Striking a civilian construction site during a major national holiday when outdoor gatherings are universal is difficult to reconcile with any of these obligations.

Legal Analysis

Additional Protocol I, Article 52 — Protection of Civilian Objects

Article 52 establishes the fundamental principle that civilian objects — all objects that are not military objectives — "shall not be the object of attack or of reprisals." Military objectives are limited to objects which by their "nature, location, purpose or use make an effective contribution to military action and whose total or partial destruction, capture or neutralization, in the circumstances ruling at the time, offers a definite military advantage."

Whether the B1 bridge met this test turns on the disputed claim that it was a planned military supply route. If that claim is false, the bridge was a civilian object and attacking it violated Article 52.

Rome Statute Article 8(2)(b)(ii) — Attacks on Civilian Objects

The Rome Statute classifies the intentional direction of attacks against civilian objects as a war crime. That charge would require showing that the bridge was not a military objective and that the attackers intended to attack it as a civilian object. Neither has been established.

Rome Statute Article 8(2)(b)(iv) — Disproportionate Attacks

Picnickers on Sizdah Bedar were foreseeable, which weighs against the attacker on precautions such as timing and warnings. A proportionality war crime, however, requires knowledge that the expected civilian harm would be clearly excessive relative to the anticipated military advantage, and there is no public evidence of what the planners expected.

Trump's Social Media Post

Trump's post — "The biggest bridge in Iran comes tumbling down, never to be used again — Much more to follow!" — is probative of a coercive purpose, but it is not proof of the elements of a war crime. Threats against infrastructure are analysed in the civilian infrastructure threats entry; the Rome Statute lists declaring that no quarter will be given as a crime, but not threats against objects as such.

Classification

This entry was formerly classified extreme. After the October 2026 legal review it is graded severe, with the war-crime question rated potential:

• Disputed military objective: The US described the bridge as a planned military supply route; Iran denies any military use. No independent body has assessed the claim.
• Unverified double tap: The report that the second strike hit first responders comes from Iranian media and has not been independently verified.
• Holiday timing: The strike occurred during Sizdah Bedar, when civilian presence near outdoor sites was foreseeable, which bears on precautions.
• Coercive rhetoric: Trump's "Stone Ages" threats and his post celebrating the destruction are evidence of a coercive purpose.
• 8 killed, 95 wounded: Civilians celebrating a national holiday were killed and injured, according to the provincial governor.