Top Capitol Hill Democrats, and a small number of Republicans, watched in alarm Saturday as the US launched a major assault on Iran, decrying Donald Trump’s call for the overthrow of another foreign government without their expressed approval.

Trump ordered the strikes on Tehran just days before the GOP-led House and Senate are each set to formally debate and vote on US military action in Iran. Democrats, along with at least three Republicans, say the president’s decision, with lawmakers scattered across the nation and not planning to return to Washington for days, raises serious questions about the legality of the attack.

“It’s a slap in the face of the United States Congress. The president has launched an illegal war when there is no imminent threat. He did not consult with Congress or allow for a debate in Congress, which even George W. Bush did,” Democratic Rep. Ro Khanna of California told CNN on Saturday morning.