U.S. Defense Secretary Leon Panetta says no decision has been made on keeping U.S. troops in Iraq past this year's deadline to withdraw.

His comments Tuesday came after media reports cited senior military officials saying Panetta had endorsed a plan to keep 3,000 American troops in Iraq as part of a training mission.

Panetta told reporters in New York that troop levels would have to be decided during negotiations with Iraqi leaders.

White House Spokesman Jay Carney said those negotiations are continuing, and that Iraq has not made a request for keeping U.S. troops in the country. He said the United States is continuing to operate under the current security agreement, which calls for all U.S. troops to withdraw by the end of this year.

There are currently fewer than 50,000 U.S. troops in Iraq, down from 140,000 in 2009.

Senators John McCain, Lindsey Graham and Joe Lieberman said in a joint statement Tuesday that 3,000 troops would be “dramatically lower” than what military leaders have said is necessary to support Iraq.

U.S. and Iraqi officials say Iraqi forces are capable of maintaining internal security but need training in using heavy weaponry to defend the country's borders, airspace and territorial waters.

Radical Iraqi Shi'ite cleric Moqtada al-Sadr has called for “military resistance” against any U.S. military trainers who remain in Iraq at the end of the year, and said any government that allows the move is “weak.” Al-Sadr's Mahdi Army militia fought U.S. troops in Iraq until 2008, when he disbanded the force and focused his movement on Iraq's political process.