With Afghan President Hamid Karzai still refusing to sign the Bilateral Security Agreement (BSA) to keep US troops in Afghanistan through 2024 and beyond, National Security Advisor Susan Rice has been dispatched to reiterate US threats to end the occupation outright.

Though Afghanistan’s Loya Jirga surprised many by signing off on the BSA over the weekend, the deal isn’t final without Karzai’s signature, and he’s insisting that should wait until the April election to choose his successor.

Rice is said to have told him that waiting until April is “not viable,” and the US already set an ultimatum for the end of the year, threatening to withdraw all troops by the end of 2014 if the deal wasn’t in place by the end of 2013.

Karzai aides say they don’t take the threat seriously, and it’s not surprise. Despite President Obama repeatedly raising the “zero option” during talks with Karzai to try to get better terms out of him, the Pentagon has confirmed time and again that leaving isn’t even being considered.

The White House reports that Karzai is laying out new conditions for his signature, seeking some unspecified changes to the deal, and while they’re insisting on the deal as currently written, there’s no reason to think Karzai will capitulate now, having made his position on one of the last major issues of his presidency so publicly clear.