This is an excerpt from a fuller discussion on the president’s constitutional war powers in a report available here.
Under the 1973 War Powers Resolution once the president notifies Congress that they have introduced the U.S. armed forces into hostilities, the president must terminate these hostilities within 60 days unless Congress has authorized their continuation.
Throughout the years since its enactment, presidents on both sides of the aisle have sought to circumvent the War Powers Resolution’s requirement to end the use of military force within 60 days in order to justify using lethal force abroad beyond this time limit without congressional authorization.
One effort has been to claim that attacks against the same targeted group or country, sometimes within days of each other should be seen as discrete events that quickly start and conclude rather than part of a broader campaign of hostilities that would trigger the 60-day clock. This approach has been described as a “renewed clock” and “salami slicing.” Another effort has been to contend that U.S. forces were already in a particular area before hostilities commenced there and as such were never “introduced” into hostilities, eliminating the need to discontinue military force after 60 days.
A further attempt to avoid the War Powers Resolution’s time limits has involved arguing that the use of lethal force by the U.S. military did not constitute “hostilities” at all. Examples include the 2013 Obama administration claim that U.S. airstrikes in Libya were not “hostilities” because the scope of the mission and risks of escalation and harm to U.S. forces were limited in nature. In 2026, the Trump administration also claimed that lethal strikes targeting boats in international waters allegedly carrying illegal narcotics were both part of an armed conflict (the technical legal term for “war”) while also not amounting to “hostilities,” citing a lack of risk of harm to U.S. service members.
These claims are incompatible with the intent of both the Constitution’s framers and that of Congress in passing the War Powers Resolution.
The framers reserved only a limited defensive power to use force to the president, not the authority to conduct certain classes of lethal military operations and wars without congressional approval based on their anticipated harm to U.S. service members. Further, a House Foreign Affairs Committee report that accompanied the War Powers Resolution explained that the term “hostilities” was intended to apply to conduct that fell below the threshold of war:
The word hostilities was substituted for the phrase armed conflict during the subcommittee drafting process because it was considered to be somewhat broader in scope. In addition to a situation in which fighting actually has begun, hostilities also encompasses a state of confrontation in which no shots have been fired but where there is a clear and present danger of armed conflict.
In addition to this pre-enactment legislative history, Congress has also passed post-enactment resolutions under the WPR that broadly define “hostilities.” This includes the 2019 Yemen War Powers Resolution, which defined “hostilities” as including “in-flight refueling of non-United States aircraft conducting missions as part of the ongoing civil war in Yemen” and the 2020 Iran War Powers Resolution, which said that the targeted killing of Iranian general Qasem Soleimani by drone amounted to “hostilities.”
Finally, on numerous occasions, the executive branch has confirmed the understanding that “hostilities” can occur when there is minimal risk of harm to U.S. forces it its own 48-hour reports under the War Powers Resolution. Examples include the Clinton administration’s 1998 strikes in Afghanistan and Sudan in response to al Qaeda’s bombing of U.S. embassies in Kenya and Tanzania, the Obama administration’s 2016 strikes on Houthi facilities in Yemen, and the first Trump administration’s strikes in 2017 and 2018 against the Syrian government in response to its use of chemical weapons.
As such, the claim that certain lethal military conduct falls below the level of force required by the term “hostilities” is contrary to the Constitution, the intent of Congress in passing the WPR, and subsequent congressional and executive branch practice.
