Though presidents have pushed the boundaries of their unilateral authority before, this action by President Trump is arguably unprecedented. When President Obama participated in the NATO strikes in Libya, at least the operation was undertaken with allies and approved by the United Nations Security Council. (He later stated that the operation was the worst mistake of his presidency.) When President George W. Bush invaded Iraq in 2003, his international support was tenuous, but he had clear Congressional authorization. In fact, the closest recent precedent for the current operation is President Trump’s own earlier decisions to strike Syrian government targets in April 2017 and again in April 2018—without either Congressional or international support. But those strikes were relatively minor in comparison and did not risk setting off a new regional war.

In 1973, after discovering President Richard Nixon’s secret bombing campaign in Cambodia, Congress took steps to reclaim its power by passing the War Powers Resolution, which requires the president to report to Congress whenever armed forces are introduced “into hostilities or into situations where imminent involvement in hostilities” and to terminate any hostilities after sixty days unless authorized by Congress. The effectiveness of the resolution has since been undermined by, among other things, fights over the meaning of “hostilities.” Congress must now act again to not only reject the illegal use of force represented by the decision to kill Soleimani but also to reassert its constitutional role in the decision-making process that takes the nation to war. If Congress fails to effectively press back against this unconstitutional assertion of unilateral authority, it will set a precedent that will put the greatest destructive power the world has ever known in the hands of a single man.