Iraq's foreign minister says negotiators are "on the brink" of reaching a long-term security pact with the United States that will decide the fate of American troops in Iraq.

Hoshyar Zebari says the Iraqis are insisting on the inclusion of a "clear timeline" for the withdrawal of U.S.-led forces. But he refused to give any dates.

Zebari told journalists Sunday that the main sticking points have been over the authorization of military operations and sovereignty issues. But he says he's optimistic that both sides "are compromising on all these issues."

National Security Council Spokesman Gordon Johndroe told FOX News that while progress is being made no agreement has been finalized.

"Discussions continue between the United States and Iraq on a bilateral agreement. As the Foreign Minister knows, we are only now able to discuss conditions-based time horizons because security has improved so much. This would not have been possible 18 months ago. We all look forward to the day when Iraqi Security Forces take the lead on more combat missions, allowing US troops to serve in an overwatch role, and more importantly return home."

U.S. acceptance — even tentatively — of a specific timeline would represent a dramatic reversal of American policy in place since the war began in March 2003.

The Associated Press contributed to this report.