NATO Secretary-General Anders Fogh Rasmussen has joined the US calls for Afghan President Hamid Karzai to sign the Bilateral Security Agreement (BSA), warning he risks an end to the “Afghan mission” if he doesn’t sign it before the year’s end.

The BSA would govern US military present beyond 2014, and is intended to ensure US forces remain in Afghanistan “through 2024 and beyond.” NATO will seek a similar pact, but only after the US deal is in place.

Karzai, whose term in office ends in April, insists he won’t sign before the elections, and wants concessions to end US night raids and drone strikes. The US insists the deal must be signed by the end of this month or else.

Pentagon officials have repeatedly said that the “zero option” of leaving after 2014 hasn’t been considered, but the Obama Administration has repeatedly thrown the prospect in Karzai’s face when it wants to speed up an agreement.