WASHINGTON  - US officials bleakly warned Afghan leaders Friday that the failure to sign a new security pact this year with the United States could jeopardize crucial aid to the war-torn country.

“We have long made clear that we need to get a Bilateral Security Agreement done this year,” White House spokesman Jay Carney told reporters.  “We’ve made clear that it’s imperative that we do it as soon as possible, and further delay is not practical nor tenable,” he said, renewing calls for the pact to be signed “as soon as possible.” A failure to sign the deal “would be seen as a signal to the world that Afghanistan is not committed to a partnership with its supporters,” State Department spokeswoman Jen Psaki said in even stronger comments. And she warned such a move could be seen as a sign that President Hamid Karzai and his team are willing to jeopardize all of the financial and practical help that has been offered. Kabul and Washington have agreed a joint draft of the pact, which governs the presence of US troops in Afghanistan after 2014 and which is being debated by a council of Afghan elders.

US commanders see nailing down the deal as essential to allowing them to begin planning the role of US and international forces after Afghans take on responsibility for frontline combat in late 2014. But Karzai, despite owing his rule to the US intervention to overthrow Afghanistan’s former Taliban regime, has proved a unpredictable ally. This week he dismayed his American partners by declaring after months of tough negotiations that the security deal, even if endorsed by the loya jirga council, could not be signed until his successor is elected in April next year. “The United States needs adequate time to plan a potential military mission with our NATO allies, and the Afghans have an election coming up,” Carney said.

“The bottom line is that we need to conclude the agreement with signature between our two governments as quickly as possible, and certainly by the end of this year,” he said.  “Failure to conclude the BSA by that point would make it impossible for the United States and our allies to plan for a presence post-2014.” Psaki also stressed that Washington believes Afghans wanted assurances about the make-up of a US troop presence in the future. “The Afghans also have an election coming up and have said they want certainty about whether the United States will be there to support them post-2014.” US President Barack Obama has not yet made a decision on how many troops would be left behind in Afghanistan to train and equip Afghan forces once the international combat teams are withdrawn at the end of next year. But asked whether the lack of a BSA deal would make the option of leaving no troops behind more likely, Psaki replied it “makes it challenging to have a post-2014 presence, yes.”