The United States uses the Manas transit center as a gateway for troops heading to Afghanistan and to stage aerial refueling. The base is adjacent to Kyrgyzstan's main international airport, also called Manas, just outside the capital of Bishkek.

President Almazbek Atambayev, elected last year to lead the landlocked former Soviet republic of 5.5 million people, has said he has no intention of renewing the U.S. lease on the base when it expires just over two years from now.

During closed-door meetings with Kyrgyz officials, Panetta encouraged discussions on the Manas transit center but didn't propose any particular plan, something the United States and Kyrgyzstan would need to work out, a U.S. official said.

In public remarks at the start of the meetings, Busurmankul Tabaldiev, the secretary of the Kyrgyzstan's Defense Council, echoed his president's position, saying "there should be no military mission" after 2014. He said the airport was a civilian, commercial enterprise.

A second U.S. official, speaking on condition of anonymity, said earlier there were no negotiations at this point to keep Manas past 2014.

Still, the official suggested that the Pentagon wasn't taking Atambayev's position as the final word on Manas, saying before the talks there may be some "wiggle room."

U.S. combat troops are withdrawing from Afghanistan through the end of 2014, the same year the Manas lease expires. But the withdrawal calendar is still unclear and troops may be moving out of Afghanistan in the months after the lease expires.

Losing Manas could complicate logistics for Washington. It would also be sure to please the Kremlin, which views former Soviet Central Asia as its sphere of influence.

Former Kyrgyz President Kurmanbek Bakiyev, ousted in an April 2010 revolution, promised to close the base after receiving a financial assistance package from Moscow in 2009. He reversed this decision after securing higher U.S. payments, which rose from $17.5 million to $60 million annually.