Updated

BAGHDAD -- The top American military officer said Monday that any agreement to keep U.S. forces in Iraq past a 2011 deadline would be reached only after Iraqi officials form a new government -- a laborious process that began after parliamentary elections in March.

After meeting with Iraqi Prime Minister Nouri al-Maliki, Adm. Mike Mullen congratulated al-Maliki for what Mullen called steady progress to build a government representing the country's diverse ethnic and religious groups.

Al-Maliki will lead that government after months of horse-trading and political paralysis. He must announce the nation's new leaders by Dec. 25 under a deadline required by Iraq's constitution.

"He's the prime minister, he's got to work though some of these details and he's doing it," Mullen told reporters during a Christmas season visit with troops.

Mullen, chairman of the U.S. Joint Chiefs of Staff, met with al-Maliki for about 20 minutes and discussed what the two countries' military relationship might be after the scheduled withdrawal of U.S. forces next year.

"I would not prognosticate that it's force level A, B or C," Mullen said later.

The U.S. military has an agreement with the Iraqi government to leave by the end of 2011.

However, U.S. Defense Secretary Robert Gates says he is open to the idea of keeping troops in Iraq past that deadline if Iraq requests it.

A military official familiar with the meeting said Mullen and al-Maliki did not discuss specifics, such as the possibility of a residual U.S. force after the agreed-upon exit deadline.

The official spoke on condition of anonymity because he was not authorized to release information publicly.

Mullen toured a U.S. base and took questions from soldiers.

Al-Maliki on Saturday repeated his opposition to altering the withdrawal agreement because Iraqi forces are capable of taking care of the country's security. But he has stopped short of pledging to not ask U.S. troops to stay, as many of his fellow Shiite Muslim political allies demand.

Jawad al-Bolani, Iraq's Interior Minister, told reporters Monday that Iraq's progress in managing its own security means that "Iraqi security troops are ready and capable of filling the vacuum in full as they were in the past years."

A spike in violence, however, has underscored the strength of extremists. Mullen's visit came as a suicide bomber killed two pilgrims and injured 13 north of Baghdad during an annual religious ritual for Shiite Muslims.

Lt. Gen. Robert Cone, commander of operations for the 50,000 American troops still in Iraq, estimated the number of daily attacks at about 15 -- far fewer than the scores each day just a few years ago.

But he said Al Qaeda in Iraq remains able to nimbly regenerate itself when U.S. or Iraqi forces ease pressure on the terror group and allied insurgents.

He said he anticipated the U.S. presence in Iraq will mostly be a "political force" after 2011, despite continuing daily violence.

"Where we are today in Iraq, we have paid for in blood," he said.

Officials with the U.S. Embassy in Baghdad sidestepped the issue of the future role of the American military. Officials said diplomats were more focused on the morass of political challenges ahead.