With negotiations over terms for some U.S. forces to remain in Afghanistan after next year at an impasse, Secretary of State John F. Kerry made an unannounced visit to the Afghan capital on Friday to bargain directly with Afghan President Hamid Karzai.

Kerry, who has a long relationship with the mercurial Afghan leader, is trying to help bridge the last sticking points that have prevented the two countries from reaching a deal, State Department officials traveling with Kerry said.

Talks are expected to continue after his visit, but Kerry will stress the need secure a deal by the end of this month, officials said.

“This is not about Secretary Kerry coming in to close a deal,” said one official, who spoke on condition of anonymity to preview the U.S. arguments.

Talks on a security agreement are stalled over long-standing Afghan demands for greater control and access to U.S. intelligence and U.S. insistence that remaining forces not be subject to Afghan law, Washington Post informs.

The “bilateral security agreement” (BSA) is supposed to assure Afghans of an ongoing U.S. commitment and to protect the estimated 5,000 to 10,000 U.S. forces expected to carry out training and counter terrorism missions after the NATO-led international mission ends in 2014.