Donald Trump isn't the first president to order military strikes without congressional approval. But his decision to bomb Iran comes at a uniquely volatile moment - both at home and abroad.
Overseas, the U.S. risks deeper entanglement in the Middle East if fighting erupts again between Israel and Iran. At home, Trump continues to sidestep oversight, showing little regard for checks and balances.
His move has reignited a decades-old debate over the War Powers Act, a law passed in the early 1970s meant to divide authority over military action between Congress and the president. Critics say Trump violated the act by striking with little input from Congress, while supporters argue he responded to an imminent threat and is looking to avoid prolonged conflict.
Even after Trump announced late Monday that a "complete and total ceasefire" between Israel and Iran would take effect over the next 24 hours, tensions remained high in Congress over Trump's action. A vote is expected in the Senate later this week on a Democratic Iran war powers resolution that is meant to place a check on Trump when it comes to further entanglement with Iran.
Here's a closer look at what the act does and doesn't do, how past presidents have tested it and how Congress plans to respond: