Rasmussen said at the start of a NATO ministerial meeting in Brussels he welcomed the Afghan Loya Jirga's endorsement of the bilateral security agreements. He said in a statement he looks forward to "its timely signature."
The Loya Jirga, a tribal council, announced its support for the agreement in November. The U.S. government has pressed for a resolution by year's end in order to coordinate its mission with NATO allies. The Afghan government said it may wait until 2014 elections to ratify the agreement.
"Deferring the signature of the agreement until after next year's election is not viable," U.S. State Department spokeswoman Jen Psaki told reporters Monday.
Psaki said a delay meant the United States and NATO allies would lack the "clarity" they need to consider any military presence beyond 2014.
"It is clear that if there is no signature on the legal agreement, there can be no deployment and the planned assistance will be put at risk," Rasmussen said. "It is my firm hope and intention therefore to continue our efforts to support Afghanistan, once these agreements are concluded."