Newly introduced this week in both the House and the Senate, a new bill being sponsored by Congressional Democrats would restrict the ability of the United States to launch nuclear first strikes, forbidding a sitting president from unilaterally ordering such strikes without a Congressional declaration of war.

Sen. Edward Markey (D – MA), who introduced the bill in the Senate, argued that the legislation is needed because President Trump has “suggested that he would consider launching nuclear attacks against terrorists,” insisting that giving the president unilateral control over the arsenal gives him that option, and risks “unintended nuclear escalation.”

It’s not at all clear that Trump would seriously consider a nuclear first strike against a terrorist group, however, and recent comments from Trump have centered on calls to negotiate a disarmament agreement with the Russian Federation. Still, the bill would limit nuclear strikes not just by Trump, but by other future presidents.

The legislation is seen as unlikely to pass in a Republican-dominated Congress, and there is as yet little sign of serious bipartisan support. The question of a US policy not to strike first with nuclear weapons has been a contentious one, with President Obama considering a pledge not to do so at all, and several more hawkish cabinet members warning it would be a “sign of weakness.”