The following are statements from key lawmakers:

Senate Armed Services Committee Chairman Roger Wicker, a Mississippi Republican, applauded the operation but cautioned that the United States now faced “very serious choices ahead.”

Senate Foreign Relations Committee Chairman Jim Risch, Republican of Idaho, said: “This war is Israel’s war, not our war, but Israel is one of our strongest allies and is disarming Iran for the good of the world.” Risch added: “This is not the start of a forever war. There will not be American boots on the ground in Iran.”

“This is not constitutional,” conservative Republican Representative Thomas Massie of Kentucky said on social media. He was referring to the power of Congress to declare war on foreign countries.

US House of Representatives Speaker Mike Johnson, a Republican of Louisiana, said, “The president gave Iran’s leader every opportunity to make a deal, but Iran refused to commit to a nuclear disarmament agreement.”

“The president’s decisive action prevents the world’s largest state sponsor of terrorism, which chants ‘Death to America,’ from obtaining the most lethal weapon on the planet.”

US House Democratic Leader Hakeem Jeffries said: “President Trump misled the country about his intentions, failed to seek congressional authorisation for the use of military force and risks American entanglement in a potentially disastrous war in the Middle East.”

“Donald Trump shoulders complete and total responsibility for any adverse consequences that flow from his unilateral military action,” Jeffries said.

Democratic Representative Alexandria Ocasio-Cortez of New York said: “The president’s disastrous decision to bomb Iran without authorisation is a grave violation of the Constitution and Congressional War Powers. He has impulsively risked launching a war that may ensnare us for generations. It is absolutely and clearly grounds for impeachment.”

Senate Majority Leader John Thune, a South Dakota Republican, said: “I stand with President Trump.”

Democratic Representative Rashida Tlaib of Michigan, a daughter of Palestinian immigrants, said: “President Trump sending US troops to bomb Iran without the consent of Congress is a blatant violation of our Constitution. The American people do not want another forever war. We have seen where decades of endless war in the Middle East get us - all based on the lie of ’weapons of mass destruction.”

Democratic Senator Tim Kaine of Virginia said the U.S. public “is overwhelmingly opposed to the US waging war on Iran” and said Trump displayed “horrible judgment.”

Max Rose, a former Democratic member of Congress who now is a senior adviser to the progressive veterans’ group “VoteVets,” said: “Trump’s decision to launch direct strikes against Iran without congressional authorisation is illegal.” Rose added: “This conflict is his and the Republicans who have abrogated all their responsibilities.”