Suppose President Biden came before Congress to announce that ending the war in Afghanistan was only the beginning. In recent years, the United States has used force on the ground or conducted strikes from the air in at least nine countries: not only Afghanistan, but also Iraq, Kenya, Libya, Mali, Pakistan, Somalia, Syria and Yemen. These wars go on in part because one person wages them. Congress has abdicated its constitutional duty to determine whether, where and whom America should fight.

Mr. Biden inherited this situation, but he need not perpetuate either the ongoing wars or the legal evasions that enable them. He could tell Congress this: It has six months to issue a formal declaration of the wars it wants to continue, or else the troops (and planes and drones) are coming home.

Were he to deliver such an ultimatum, Mr. Biden would, in a stroke, usher in a new era of U.S. foreign policy. Of course, the president would be attacked for shirking his responsibility. But the responsibility to declare war rightly belongs to Congress, and if Congress keeps passing the buck, then Mr. Biden, his successor or the voting public ought to insist that it fulfill its obligations. Otherwise, a lone individual will continue to direct the largest military the world has ever seen, while 333 million Americans fight, pay, and mostly watch our wars unfold.

If this idea sounds revolutionary, the real revolution came when Congress stopped declaring war altogether. For the framers, the clause giving Congress the power to “declare war” ranked among the Constitution’s key innovations. James Madison considered it the wisest part of the document, because he thought the executive was “the branch of power most interested in war, & most prone to it.”

Prominent Americans once sought to raise the Constitution’s bar even higher. Following World War I, Representative Louis Ludlow of Indiana wanted to put war powers directly in the hands of the people; he proposed a radical constitutional amendment that would have required the entire country to vote on whether or not to declare war. For years, more than 70 percent of the public supported the measure, but the House of Representatives rejected it by a narrow margin in 1938.

In the wake of the attack on Pearl Harbor, Congress declared war. It has never done so again. For the next eight decades, the country traveled down a path diametrically opposed to the one Representative Ludlow envisioned. Setting out to police the world, presidents circumvented the congressional constraints once erected to stand in their way. As a result, when pundits cast blame for the chaos in Afghanistan, they debate which presidents to fault most: those who started and extended the war, or those who have sought to bring it to a close. Such finger pointing reinforces one cause not just of this particular disaster, but of the many metastasizing conflicts the country has undertaken since Sept. 11: the purposeful submission of Congress to the imperial presidency.