President Pulls Lawmakers Into Box He Made

 More than once, President Obama has confided to aides that he regards Syria as one of those hellish problems every president faces, where the risks are endless, the choices are all bad, and the pressure to do something is unrelenting.

On Saturday, those treacherous crosscurrents were on vivid display in the Rose Garden. After two years of resisting deeper involvement in Syria, Mr. Obama finally decided to order a military strike — only to put his order on a shelf while he seeks Congressional approval.

For Mr. Obama, who presented his most fervent case yet that Syria needed to be punished for a deadly chemical weapons attack, the ironies are deep: having at last convinced himself of the imperative to act, he concluded that he had not secured enough political support at home to fire Tomahawk missiles at Syria.

As a former senator who built his foreign policy on extricating the United States from wars, he now faces one of the greatest challenges of his career in persuading Congress to thrust the United States into another conflict in the Middle East.

To a large degree, much of Mr. Obama’s quandary is that he boxed himself in by setting a “red line” on the use of chemical weapons by Syria, a line he now feels obliged to enforce to preserve his credibility. But the path to this messy moment has been complicated by more than an ill-advised utterance on Syria.

Throughout his presidency, whether the goal was closing the military prison in Guantánamo Bay, Cuba, or backing the NATO air campaign in Libya, Mr. Obama has proved better at articulating legal principles than at managing the politics that could help him defend those principles.

Syria has also laid bare a fundamental contradiction: a president who is a staunch defender of international law on issues like the use of chemical weapons but also a reluctant warrior who is desperate to pull the United States out of the morass of the Middle East.

That ambivalence has been palpable in Mr. Obama’s public statements on possible military action. While Secretary of State John Kerry has delivered a thunderous case against President Bashar al-Assad, his boss has been circumspect, sprinkling his words with caveats about the modest scale of the operation and acknowledgments of the nation’s combat fatigue.

“We don’t have good options, great options, for the region,” the president said in an interview Wednesday on the PBS program “NewsHour,” before describing a “limited, tailored” military operation that he said would amount to a “shot across the bow” for Mr. Assad’s government.

There are other reasons for his predicament, not least the legacy of the Iraq war, which contributed to the devastating vote against military force in the British Parliament. Then there is the intransigence of Syria’s big allies, Russia and China, which has precluded the endorsement of the United Nations Security Council, where both countries hold a veto.

But Mr. Obama himself has seemed torn. Having warned Mr. Assad in March that his use of chemical weapons would be a “game changer,” the president reacted to earlier, smaller-scale attacks by agreeing to supply arms to Syria’s rebels covertly, which meant the White House never openly discussed it.

Some analysts say that Mr. Obama’s determination even now to divorce military action from broader engagement in Syria may have complicated his effort to rally international support.

“We’re telling people, we still don’t want to get involved, we just want to punish this guy,” said Vali R. Nasr, the dean of the Johns Hopkins School of Advanced International Studies. “The reason people aren’t lining up with us is that they don’t have trust in our policy.”

At home, Mr. Obama has not felt political pressure to act. Recent polls show that a majority of Americans do not support military action against Syria, even if its government used chemical weapons. They are more closely divided if they are asked about a missile strike that would pose no risk to American lives.

When his national security staff begin debating how to respond to the Aug. 21 chemical weapons attack, Mr. Obama set off on a bus tour of Pennsylvania and upstate New York, where he barely mentioned Syria but told an audience that law school should be shortened from three years to two.

With Congress, the president’s effort to sell the military strike has been weakened by the belief, particularly among rank-and-file members, that he did not adequately consult them before committing American forces to the Libya air campaign in 2011.

Mr. Obama has been wrestling with how the United States should use its military might since the start of his presidency.

In 2009, in accepting the Nobel Peace Prize, the president made a case for using force to avert episodes of mass atrocities, saying: “Inaction tears at our conscience and can lead to more costly intervention later. That’s why all nations must embrace the role that militaries with a clear mandate can play to keep the peace.”

But two years later, having reluctantly backed the NATO campaign in Libya, Mr. Obama was quick to draw limits.

“We cannot prevent every injustice perpetrated by a regime against its people,” he said in a speech on the Middle East, “and we have learned from our experience in Iraq just how costly and difficult it is to impose regime change by force.”

Advisers to Mr. Obama say the difference between the Iraq war and the likely Syria operation is central to understanding him: one was a large-scale invasion aimed at ousting Saddam Hussein; the other would be a limited operation to enforce a violation of the international norm against the use of chemical weapons.

“What’s missing in this discussion is that this is not something with a long timeline attached to it,” said Benjamin J. Rhodes, a deputy national security adviser. “The use of very limited military force to enforce U.S. security interests and global norms is a very different model than the war in Iraq or the war in Afghanistan.”

Mr. Obama’s legalistic approach has been evident in his comments in the last week. So, too, has been his steadfast conviction that broader military involvement would only make matters worse.

“The world has an obligation to make sure that we maintain the norm against the use of chemical weapons,” he said Friday. On PBS, he talked about Syria’s “sectarian arguments that have spilled over into bloodshed and have escalated over the last couple of years” — an analysis that could have been applied, word for word, to Iraq. That comparison is never far from Mr. Obama’s mind, his advisers say, and for a politician who built his national career on his opposition to the Iraq war, it is a telling one.

Given the intractable nature of the Syrian conflict and the deep-rooted suspicions in the Arab world about American motives, some former administration officials said that Mr. Obama’s limited intervention would inevitably create a new set of problems.

“If the scope of the attacks is too narrow,” said Steven Simon, who until this year was the senior director for the Middle East at the National Security Council, “Obama is going to end up with a gloating Assad. If it’s too sweeping, it’s going to raise questions about regime change and American ownership. How do you find the sweet spot?”

For that reason, officials expect Mr. Obama to follow his military action with a renewed diplomatic effort. The trouble is, the fracturing of Syria into warring, increasingly radical factions makes diplomacy even harder.

For those who argued that Mr. Obama should have done more to support the rebels a year ago, his quandary seems sadly inevitable.

“What was eminently predictable has come to pass,” said Anne-Marie Slaughter, former director of policy planning at the State Department and the incoming president of the New America Foundation. “Because of the way it’s evolved, it is an incredibly complicated problem.”