WARSAW, Poland (AP) — Defense Secretary Chuck Hagel hinted Thursday at growing U.S. impatience with Afghan President Hamid Karzai for his refusal to sign an accord permitting American troops to remain in his country after the U.S. combat mission ends in December.

Hagel told reporters that at some point Karzai’s indecision will interfere with Washington’s need to plan the post-2014 military mission that Karzai himself has said he favors. The Obama administration has indicated it might be willing to keep as many as 10,000 U.S. troops in Afghanistan for some time after 2014 to train and advise Afghan forces.