Mission Accomplished. Finally.

The long war provoked by the attacks of Sept. 11 is over. The congressional resolutions authorizing combat in Afghanistan and Iraq no longer justify military operations in either country — or anywhere else. U.S. President Barack Obama gained office by denouncing his predecessor’s assertion of unilateral power to commit the nation to an endless war against terror. Yet, despite the absence of legislative authorization, Obama is moving down George W. Bush’s path to unilateral warfare. This is the real existential threat to American democracy. And it’s why the best way to honor the victims of 9/11 is for Americans to rededicate themselves to the Constitution, which requires the president and Congress to hammer out a new resolution defining war aims for a new decade.

The legal authority for America’s present military engagements collapsed in two stages. The first involved Iraq. When Congress authorized the use of force in October 2002, it refused to give the president a blank check. Once Saddam Hussein fell, the 2002 resolution only authorized U.S. troops to operate as part of a U.N.-sponsored occupation force. When the U.N. Security Council planned to terminate this authority on Jan. 1, 2009, President George W. Bush’s administration devoted its final months to a new agreement with Iraqi Prime Minister Nouri al-Maliki’s government to legalize continuing military operations. But this time, it cut Congress entirely out of the negotiations.

Joseph Biden, then chairman of the Senate Foreign Relations Committee, responded with a proposal declaring that any bilateral agreement with Iraq "should involve a joint decision by the executive and legislative branches." This was not strong enough for Sen. Barack Obama, who signed onto a bill proposed by Sen. Hillary Clinton that would deny all funds to any agreement not approved by both houses. As she explained, it was "outrageous that the Bush administration would seek to circumvent the U.S. Congress on a matter of such vital interest to national security."

Bush simply ignored these protests and continued his end run around the Constitution. His lame-duck deal with Maliki went into effect on Jan. 1, 2009, and once they took office, Obama, Biden, and Clinton conveniently forgot their objections. They embraced the Dec. 31, 2011, pullout date established by the Bush-Maliki agreement, implicitly endorsing Bush’s power grab.

A similar pattern is now unfolding in the battle against al Qaeda — but this time, Obama will be solely responsible for the decision to cut out Congress. The legal authority for the war on terror is a congressional resolution, passed immediately after the 9/11 attacks, approving the use of force against groups that "planned, authorized, committed, or aided" the attacks on the Pentagon and World Trade Center. But a decade later, this resolution can no longer credibly support ongoing military operations.

Al Qaeda’s operatives in Pakistan are currently reeling from drone attacks that have killed a series of top commanders. Their capacity to coordinate attacks on the United States has been decimated. Official estimates place the entire Pakistan contingent at 500 or less; and the number of al Qaeda operatives in Afghanistan is fewer than 100.

These undisputed facts are a tribute to America’s success, but they severely undercut the legal basis of the current campaign in Afghanistan. The 2001 resolution targeted only the groups responsible for 9/11, and these are disintegrating before our eyes. While it also authorized assaults on countries and organizations that "harbored" the original terrorist attackers, this grant is also wearing thin. Originally, the Islamic Republic of Afghanistan provided safe harbor for Osama bin Laden, but the Taliban who then dominated the government have now fragmented into a loose coalition of rebel groups, each under independent leadership. Nobody can say which, if any, of these insurgent networks are "harboring" the tiny number of al Qaeda members remaining in the country. One thing is plain: The scale of the U.S. military effort is utterly disproportionate to the harboring problem, if there is one.

Terrorism remains a serious threat, warranting a serious strategic response. But it is no longer the Afghanistan-centered problem that Congress confronted a decade ago. If another attack hits the homeland, it will likely come from terrorists based in Somalia, Yemen, or some other failed state, acting independently of al Qaeda’s increasingly disorganized "central command." Yet these new groups simply aren’t within the scope of Congress’s decade-old authorization. Now is the time for the president to declare victory in the war against al Qaeda and return to Congress for a new resolution dealing with the new threats of the coming decade, in a world where trillion-dollar wars are an unaffordable luxury.

Yet Obama seems reluctant to declare that, at long last, Americans have indeed earned the right to proclaim "mission accomplished" — at least as far as this mission has been constitutionally defined by Congress on the statute books. While all presidents love to claim credit, there is something they like even more: power. As long as he pretends to be fighting yesterday’s war against al Qaeda and its vaguely defined "affiliates," Obama can continue to wield the war-making powers granted him by the 2001 resolution. Once he declares that this mission has been accomplished, the Constitution gives him no choice but to deal with troublemakers in Congress in hammering out new strategic principles for the real-world threats we face.

But if Obama chooses to preserve his short-term freedom of action, the United States will pay a terrible long-term price. In using legal fictions to transform Congress’s decade-old resolution into an open-ended authorization for unilateral war-making, he will be opening up a path for future presidents to launch major military initiatives without regard to the views of Congress or the American people. Is that what we really want?