The recent decision by U.S. President Barack Obama to seek congressional support for military action in Syria caught many, including some of his own advisers, off guard. The decision seemed not merely to violate to his immediate interests but also to contravene his own past practices. Rather than aberrational, however, the move reveals some longstanding truths about how the United States goes to war.

The first concerns Congress’ continuing relevance in military decision-making. Many analysts have long written it off. And to a certain extent, they have been right to do so. When it comes to foreign policy generally, and military action in particular, the president enjoys extraordinary power: power to unilaterally advance his own agenda; power with the public, which looks to him to chart foreign policy; and informational power, which allows the president to structure the terms and direction of any accompanying debate. Congress, meanwhile, can seem hamstrung and all but useless. The multiple veto points, partisan polarization, and pervasive gridlock predictably impede and distort even the most sober efforts to address real-world challenges.

Even so, in the domestic politics of war-making, it would be unwise to count Congress out. Obama did not have to seek congressional approval for military action in retaliation for the Assad regime’s recent alleged use of chemical weapons against his own people. But he did. And that was a prudent choice.

The advantages of consent will mostly matter in retrospect, not in the run-up to war. That is because, if Congress approves the military action, it cannot as easily criticize its effects. Just ask Secretary of State John Kerry, who stumbled through the 2004 campaign for the presidency trying to explain why he was for the Iraq War before he was against it. In the aftermath of a military action, members of Congress can use hearings, investigations, floor debates, and media appearances to make a case that a military venture failed outright or created new problems. In extreme cases, as occurred in the latter stages of the Vietnam War, all this may lay the groundwork for legislative action against the president. But even in the absence of a formal rebuke, congressional criticisms can turn the public against the president and his party, signal to U.S. allies and enemies a lack of resolve for continued military action, and upend congressional action on other aspects of the president’s policy agenda.

COUNT ON CONGRESS

The idea that Congress matters is simple enough. How it matters, though, is less understood. When it comes to military action, Congress acts mostly as a restraint. Not since the Spanish-American War, when substantial factions in Congress all but forced President William McKinley to send U.S. troops into Cuba, has Congress impelled a military deployment when the president preferred peace. Instead, congressional influence nearly always manifests in the negative, slowing the pace of some military actions and convincing presidents to altogether abandon the plans for others.

Congress’ restraining influence on presidential war-making is well documented. In my own research with the political scientist Jon Pevehouse, I have found that presidents are less likely to wage war when the opposing party controls Congress. Moreover, the length of time that it takes for the president to respond to foreign crises regularly increases when congressional majorities of the opposition party stand in his way. Likewise, according to Douglas Kriner of Boston University, presidents tend to wage shorter, more limited wars in the face of congressional opposition.

Today, Congress’ negative influence is again on display. After an upcoming vote, majorities may sign off on military action against Syria, giving Obama the domestic political cover he needs. But the approval will come at a price -- in particular, a military strike that comes a good deal later than the president, not to mention the opponents of the Assad regime and the victims of the chemical attack itself, would otherwise have preferred.

Congress’ negative influence probably also has something to do with the kind of strike that has been proposed. Obama has recommended only a limited military engagement. There has been no talk of sending ground troops or even making a prolonged commitment of material aid to the Syrian revolutionaries. As Obama took pains to emphasize, “Our action would be designed to be limited in duration and scope.” Such sentiments surely reflect the president’s own reluctance to intervene in yet another war-torn region of the globe. But still, absent the threat of congressional reprisal, Obama certainly would be acting swifter, and might well be acting with greater force, against the Syrian regime.

HAIL THE HIGHEST LAW

By seeking Congress’ prior approval for military action, Obama might be adhering more closely with the constitution. But the constitution is not the administration’s main concern. Obama’s own record consists nearly entirely of unilateral decisions on war: drawing down the Iraq War, first escalating then planning an end to the Afghanistan War, providing protective cover for Libyan revolutionaries, expanding the use of drone attacks, and waging a largely clandestine war on terror. Seeking congressional approval at this late hour of his presidency is not going to remake Obama’s own record. It certainly is not going to breath new life into the constitutional provisions outlined in Article I, which lists congressional powers. That Obama is trying to drum up congressional support now suggests fears that the immediate consequences of military action are likely to be negative and an appreciation for the exhaustion of the American public and of the nation's closest ally, the United Kingdom.

Obama’s foreign policy record is hardly unique. For the last half-century, presidents have launched dozens of major military deployments, and hundreds of smaller ones, without first securing Congress’ consent. Presidents have sought approval only intermittently, particularly when the prospective military venture was especially large, long, and risky. But even then, as President Harry Truman demonstrated in the lead-up to the Korean War, presidents have opted to work around Congress rather than directly engage it.

In military policy, Congress matters not because it retains the formal authority to declare war (which has not happened since World War II) or to raise and support armies (a power granted by the constitution but which Congress nearly always does according to the president’s wishes). Rather, Congress matters because even the most straightforward military operations -- and to be clear, the action in Syria is anything but straightforward -- are rife with dangers. And should the president misstep, members of Congress, particularly those in the opposition party, stand ready to document all of his deficiencies to the country and world.

Following a U.S. strike, we can expect things in Syria and the surrounding region to get uglier before they get better. The president wants Congress to sign off on his plans now to ensure some modicum of support later, when anti-U.S. protests flare, jihadists are emboldened, more lives are lost, and foreign leaders condemn what they perceive as further evidence of American imperialism. It is a calculated political decision. But it has nearly nothing to do with constitutional obeisance.