The United States’ early Saturday morning joint military operation with Israel against Iran divided Republicans, some praising President Donald Trump, but others warning against the possibility of getting into a foreign war.

“I am opposed to this War. This is not ‘America First,’” Rep. Thomas Massie (R-Ky.) said on X, adding that he and Rep. Ro Khanna (D-Calif.) will force a congressional vote on war. “The Constitution requires a vote, and your Representative needs to be on record as opposing or supporting this war.”

The president announced Saturday that the U.S. has begun “major combat operations in Iran,” which the defense department is calling “Operation Epic Fury.”

Trump seemed to urge regime change, encouraging the Iranian public to “take over” their government, which he claimed has continued to develop its nuclear program with plans to develop missiles to reach the U.S.

“My administration is taking every possible step to minimize the risk to U.S. personnel in the region. Even so, and I do not make this statement lightly, the Iranian regime seeks to kill,” Trump said. “The lives of courageous American heroes may be lost, and we may have casualties. That often happens in war. But we’re doing this not for now. We’re doing this for the future. And it is a noble mission.”

The president’s announcement sparked criticism from conservatives who pride themselves on being “America First.”

“The Trump admin actually asked in a poll how many casualties voters were willing to accept in a war with Iran???,” the MAGA firebrand and former close Trump ally wrote. “How about ZERO you bunch of sick fucking liars. We voted for America First and ZERO wars.”

Sen. Rand Paul (R-Ky.) said that “yet another preemptive war” had “begun in the Middle East,” stating that “the Constitution conferred the power to declare or initiate war to Congress for a reason, to make war less likely. “

“As with all war, my first and purest instinct is wish Americans soldiers safety and success in their mission,” Paul wrote. “But my oath of office is to the Constitution, so with studied care, I must oppose another Presidential war.”

But others in the GOP remained loyal to Trump, praising the president’s speech and the attack itself.

Sen. Lindsey Graham said Trump’s speech “will go down in history as the catalyst for the most historic change in the Middle East in a thousand years.”

“I echo President Trump’s call to the Iranian military, IRGC and security forces to lay down their arms. I echo his call to the Iranian people to take back their government,” Graham said. “President Trump was right when he said he’s the first president in 47 years to stand with the people of Iran and give them the backing they need.”

Sen. Katie Britt (R-Ala.) offered full support of the operation in a statement on X, calling it “a defining moment of generational leadership from President Trump to achieve sustainable peace.”

“President Trump understood what the weak could not bring themselves to say: that peace is not found in appeasement - it is won,” she continued.