WASHINGTON — As Iraq erupted in recent days, Vice President Joseph R. Biden Jr. was in constant phone contact with the leaders of the country’s dueling sects. He called the Shiite prime minister and the Sunni speaker of the Parliament on Tuesday, and the Kurdish leader on Thursday, urging them to try to resolve the political crisis.

And for the United States, that is where the American intervention in Iraq officially stops.

Sectarian violence and political turmoil in Iraq escalated within days of the United States military’s withdrawal, but officials said in interviews that President Obama had no intention of sending troops back into the country, even if it devolved into civil war.

The United States, without troops on the ground or any direct influence over Iraq’s affairs, has lost much of its leverage there. And so the latest crisis, a descent into sectarian distrust and hostility that was punctuated by a bombing in Baghdad on Thursday that killed more than 60 people, is being treated in much the same way that the United States would treat any diplomatic emergency abroad.

Mr. Obama, his aides said, is adamant that the United States will not send troops back to Iraq. At Fort Bragg, N.C., on Dec. 14, he told returning troops that he had left Iraq in the hands of the Iraqi people, and in private conversations at the White House, he has told aides that the United States gave Iraqis an opportunity; what they do with that opportunity is up to them.