A bipartisan group of House lawmakers who want to stop President Donald Trump from pulling U.S. troops from military conflicts and overseas bases are using a once-unusual tactic that has in the last three years become Congress' go-to tool.

Lawmakers from the Senate and the House have in the last three years sought to use legislation to prevent the president from pulling troops from Afghanistan, Syria, South Korea, and now Germany — unless the administration certifies that a withdrawal will not harm U.S. or allied interests.

It's an unusual reversal for Congress, which historically is far more likely to seek to force a return of American troops, not demand that they remain deployed.