TEHRAN — ​Tens of thousands of protesters flooded the streets of central London on Saturday, marking a nationwide day of mobilization to condemn the ongoing U.S.-Israeli war on Iran and demand an end to British military support.

Protesters marched from Russell Square through the heart of the city toward Whitehall, creating a sea of the flags of the Islamic Republic of Iran and Palestine while chanting slogans against what they and many observers describe as a campaign of unprovoked aggression.

The rally—organized by a coalition including Stop the War Coalition and the Campaign for Nuclear Disarmament—represented a major step up in domestic resistance in Britain to the three-week-old war.

Public anger in the United Kingdom is increasingly directed at Prime Minister Keir Starmer’s government.

Demonstrators at Richmond Terrace specifically condemned the UK’s "active complicity" in the strikes, citing the controversial authorization for U.S. forces to utilize sovereign British military bases for offensive sorties.

Critics argue that by providing logistical support and intelligence, the UK has bypassed parliamentary scrutiny and ignored the lessons of previous Western campaigns of agression in the Middle East.

The government’s stance appears deeply out of step with the British public; recent polling indicates that nearly 60 percent of the population opposes the current military campaign and rejects the use of British soil to facilitate strikes against Iran.

As the rally concluded outside Downing Street, speakers emphasized that the movement would continue to grow until the bombing ceases.

The presence of trade unionists, healthcare workers, and students underscored a broad-based rejection of the war, with many participants highlighting the irony of funding foreign military operations while domestic services remain underfunded.

The protest comes as the humanitarian situation in Iran reaches a critical threshold.

According to the latest figures released by Iran’s Health Ministry, approximately 21,000 people have been injured since the commencement of U.S.-Israeli airstrikes on February 28.

Absent an official tally, reports suggest the death toll has already surpassed 1,400, with a significant number of those casualties being civilians.

The aerial campaign has targeted major urban centers, resulting in the systematic destruction of essential infrastructure such as power plants, water treatment facilities, and residential complexes.

The human cost was defined from the outset by the harrowing Minab school massacre on the war's opening day, where successive missile strikes on the Shajareh Tayyebeh elementary school claimed the lives of 175 people—including 110 children and 26 teachers—while leaving at least 95 others wounded.