It took U.S. Rep. Thomas Massie nine minutes to respond to President Donald Trump’s announcement that he had ordered warplanes to strike Iranian nuclear facilities on Saturday, June 21. “This is not Constitutional,” the Kentucky Republican wrote on X, underscoring both the questions surrounding the president’s unilateral decision to attack Iran and a fissure in Trump’s Make America Great Again (MAGA) movement.Both the Constitution and federal law require congressional consent for military action against foreign adversaries. But Trump and his allies say he ordered the attack in response to an imminent threat, and they pushed back against dissenters.On his Truth Social website, Trump called Massie “weak,” “ineffective,” “a simple-minded ‘grandstander’” and “not MAGA,” before concluding, “GET THIS ‘BUM’ OUT OF OFFICE, ASAP!!!”War powersArticle I of the Constitution gives Congress the sole authority to declare war, as well as control over spending for military actions. However, presidents have used their authority as commander in chief of the military to send troops into conflict zones, including Korea and Vietnam, or to expand U.S. involvement in foreign combat with a formal declaration of war.Lawmakers sought to limit the president’s ability to launch or escalate military actions when they passed the War Powers Resolution of 1973. The resolution requires presidents to notify Congress within 48 hours of initiating military action and prohibits U.S. troops from participating in a foreign war for more than 60 days without congressional approval.Under the 1973 resolution, Congress has approved several military actions in recent decades, according to the fact-checking website PolitiFact. In the 1980s, lawmakers authorized President Ronald Reagan to send U.S. Marines to Lebanon. In 1991, they supported President George Bush’s decision to initiate the Gulf War. A decade later, they approved President George W. Bush’s broad war on terrorism after the attacks of Sept. 11, 2001.By contrast, President Barack Obama did not obtain congressional consent before intervening in Libya in 2011, although the United Nations Security Council had authorized military action. Likewise, Trump approved air strikes in Syria in 2017 without asking Congress for permission.Some legal experts suggested that Trump needed approval before ordering the Air Force to drop massive “bunker-buster” bombs on three Iranian nuclear sites on Saturday.“The short answer is that this is, in my view, illegal under both international law and U.S. domestic law,” Oona Hathaway, a professor of international law at Yale University, told The New York Times.Nolan Higdon, a history professor at the University of California, Santa Cruz, told ABC News that, absent a declaration of war, presidents can argue that action was necessary –– and proving otherwise is difficult.Vice President JD Vance and other Trump administration officials contended the president had the authority to order the strikes –– in part, because he had not declared war on Iran.“We’re not at war with Iran,” Vance said on NBC's “Meet the Press.” “We’re at war with Iran’s nuclear program.”Sen. Tim Kaine, D-Va., said that’s a meaningless distinction.“When you’re bombing another nation, ask them if they think it’s war,” Kaine said on CBS' “Face the Nation”. “They do. Would we think it was war if Iran bombed a U.S. nuclear facility? Of course we would.”Kaine is sponsoring a war powers resolution that would prohibit military action against Iran without congressional approval. The Senate could vote on the resolution this week.In the House, Massie, the Kentucky Republican, and Rep. Ro Khanna, D-Calif., are sponsoring their own war powers legislation.A MAGA riftSome Democratic officials said Trump made the right decision in bombing Iran, among them Sen. John Fetterman of Pennsylvania.“There’s going to be a lot of people in my party that are going to disagree with the strike in Iran, and I actually support that,” he said, according to The Hill. “I think it was entirely appropriate.”Among Republicans in Congress, most supported striking Iran. At the same time, Trump’s decision exposed a rift among followers of his MAGA movement.Several Trump supporters recalled that he campaigned on a promise to end America’s “forever wars,” including long-running conflicts in the Middle East, and to stay out of new battles. Steve Bannon, the former White House adviser who hosts the “War Room” podcast, complained that Trump has hinted that he may order additional air strikes.“I’m not quite sure (it was) the talk that a lot of MAGA wanted to hear,” Bannon said, according to The Guardian. “It sounded … very open-ended.”Rep. Marjorie Taylor Greene, R-Ga., affirmed her support for Trump while questioning the wisdom of his decision. “American troops have been killed and forever torn apart physically and mentally for regime change, foreign wars, and for military industrial base profits,” Greene wrote on X. “I’m sick of it.” Other MAGA supporters lashed out at those who opposed acting against Iran. One was Mark Levin, a Fox News host, who called Greene a “shameless nitwit.” On Bannon’s “War Room,” Greene dismissed Levin as one of the “neocons and warmongers” who convinced Trump to join Israel’s war with Iran.Trump discounted criticism from his own party, pledging to support primary challengers to Republicans like Massie. The congressman “thinks it’s good politics for Iran to have the highest level Nuclear weapon, while at the same time yelling ‘DEATH TO AMERICA’ at every chance they get,” Trump wrote on social media. “Iran has killed and maimed thousands of Americans, and even took over the American Embassy in Tehran under the Carter Administration. … MAGA should drop this pathetic LOSER, Tom Massie, like the plague!”