Crowds are gathering in Washington, New York, and other cities to condemn Trump's strikes on Iran as an illegal act of war, The Guardian reports.

Protesters have assembled across the United States, including outside the White House and in New York's Times Square, to express opposition to US military intervention in the region.

"This was not authorized by Congress, so what Trump is doing is his personal initiative; it makes him a fascist and turns the country into a fascist state," said protester Sue Johnson.

Dozens of protests were organized by a coalition of left-wing groups, including ANSWER Coalition, National Iranian American Council, 50501, American Muslims for Palestine, People's Forum, Palestinian Youth Movement, CodePink, Black Alliance for Peace, and Democratic Socialists of America.

The coalition also announced additional "emergency protests" on Saturday in Atlanta, Baltimore, Boston, Chicago, Cincinnati, Denver, Las Vegas, Los Angeles, Miami, and Minneapolis. On Sunday, rallies are planned in several other cities, including Albany (NY), Ellensburg (VA), Chattanooga (TN), Decorah (IA), Gainesville (FL), and Springfield (MO).

Organizers released a statement saying: "Trump's unprovoked, illegal attack on Iran is an act of war that threatens unimaginable casualties and destruction. But the people of this country reject yet another endless war and will take to the streets right now to make our voices heard."

New York City Mayor Zohran Mamdani earlier in the day said the US and Israeli strikes on Iran "represent a catastrophic escalation of an illegal war of aggression. Bombing cities. Killing civilians. Opening a new theater of war. Americans don't want this. They don't want another regime change war."

The American Civil Liberties Union joined dozens of Democratic lawmakers in demanding that Congress take immediate action to halt Trump's unconstitutional use of military force against Iran. The civil rights organization noted that it has "consistently argued — from Vietnam to the war in Afghanistan, both Iraq wars, the military operation against Libya, and the ongoing use of force in Iraq, Syria, Yemen, and Somalia — that the Constitution is clear: decisions to use military force require specific prior authorization from Congress."

As the New York Times notes, public support for a US attack on Iran was low even before Trump and Israel began striking Iran. A majority of Americans said they either opposed such action (49 percent) or were unsure (30 percent), according to a University of Maryland poll conducted two weeks ago.

Doubts were also evident among Republicans: 40 percent supported a strike, 25 percent were opposed, and 35 percent said they didn't know.

An AP-NORC poll conducted last week showed low confidence in Trump's ability to handle military force responsibly. Only 27 percent of Americans — and just 14 percent of political independents — said they trust him to make the right decisions on the use of military force abroad.

At the same time, the poll showed that nearly half of all American adults are extremely or very concerned about Iran's nuclear program, with another 31 percent moderately concerned.