(WASHINGTON) — The Senate approved a bipartisan measure Thursday limiting President Donald Trump’s authority to launch military operations against Iran. The measure, authored by Sen. Tim Kaine, D-Va., says Trump must win approval from Congress before engaging in further military action against Iran. Eight Republicans joined with Democrats to pass the resolution by a 55-45 vote. Kaine and other supporters said the resolution was not about Trump or even the presidency, but instead was an important reassertion of congressional power to declare war. While Trump and other presidents “must always have the ability to defend the United States from imminent attack, the executive power to initiate war stops there,” Kaine said.