National Security Adviser Susan Rice on Tuesday said the U.S. was surprised by Afghan President Hamid Karzai’s new conditions for signing a postwar security accord and that she was “sad and disappointed” by the delay.

“It was stuff we had not seen or heard before in some respects,” Rice said in an interview with Afghanistan’s Tolo TV.

“I must say that I was sad and disappointed that by the end of our meeting, it was clear that he is not yet prepared to sign that agreement promptly. I hope he will do so,” she added.

Rice’s comments came a day after she met with Karzai and urged him to sign the Bilateral Security Agreement, which will govern the role for U.S. military forces in Afghanistan after the NATO mission ends in 2014.

The deal was hammered out after a contentious negotiation and approved by a council of Afghan elders earlier this week. But Karzai is refusing to sign the agreement, citing “mistrust” between him and the U.S., and has said he would leave it to his successor.

The White House is pressing the Afghan leader to sign the document by the end of the year, and on Monday, Rice warned Karzai that any delay would jeopardize U.S. plans to provide humanitarian assistance and military training for Afghan forces.

On Tuesday, Rice declined to spell out what actions the U.S. would take if Karzai fails to sign, but said the U.S. would have no choice but to consider the withdrawal of all military personnel after 2014.

“I don’t want to really get into hypotheticals about what might happen,” said Rice. “If the agreement isn’t signed promptly, what I said to the president [Karzai] is we would have no choice, we would be compelled by necessity, not by our preference, to have to begin to plan for the prospect that we will not be able to keep our troops here.”

The administration has insisted they will not reopen negotiations on the security deal.

“We’ve concluded the negotiation of the agreement,” said Rice. “President Obama sent a letter to President Karzai. So the text is concluded. The negotiation is done.”