Editor's note: Read all of Security Clearance's coverage of the 2012 NATO summit in Chicago. Follow our reporting and other key NATO tweets with our NATO summit Twitter list.
By Mike Mount and Elise Labott reporting from Chicago
The United States will not agree to pay the stiff fees Pakistan is asking in order to open up NATO supply routes into Afghanistan, U.S. officials told CNN Saturday.
Ahead of a NATO summit on Afghanistan's future, Pakistan is requesting $5,000 per truck as a condition to reopen the supply lines between the two South Asian countries, U.S. officials said.
The new cost is a sticking point in week-long negotiations between Washington and Islamabad to open the roads, known as the ground lines of communication or GLOCs. U.S. officials say the fees are inflated.
"We're hopeful the GLOCs will be reopened soon, but we're not going to agree to unreasonable charges. The Pakistanis understand that," said a senior defense official who is not authorized to speak publicly about the talks.
Previously, the United States had been paying just a "small fraction" of the requested fee, officials said.
Defense Secretary Leon Panetta said the United States would refrain from such a deal due to budgetary restraints.
"Considering the financial challenges that we're facing, that's not likely," Panetta told the Tribune newspaper service earlier in the week.
Pakistan shut down the supply routes - stretching from Afghanistan through the lawless western tribal regions of Pakistan and down to the southern port of Karachi - last November after dozens of its troops were killed in a mistaken U.S. airstrike.
The routes offer a shorter and more direct route than the one NATO has been using since November that goes through Russia and other nations and avoids Pakistan altogether.
Pakistani Ambassador Sherry Rehman said Washington was paying more for the northern route.
"Perhaps, if you look at the end route where your trucks move through much longer, but I believe the double of that amount is paid," Rehman said.
But U.S. officials said the nations along the northern route do not receive "Coalition Support Funds," which should allow Pakistan to lower costs.
The supply route will take on more significance as NATO troops prepare to depart Afghanistan by 2014 and will have to move heavy equipment and supplies out of Afghanistan for shipment from Karachi.
The drawdown forms a big part of the agenda at the NATO summit in Chicago starting Sunday, which Pakistani President Asif Ali Zadari is attending.
Pakistan did allow four trucks containing supplies destined for the U.S. Embassy in Kabul to cross its border Friday, the first in six months.
Rehman called it a first step.
"So this is a new beginning. And, obviously, I bring good tidings," Rehman said.
But U.S. officials were less optimistic. Besides the cost, said one official familiar with the talks, there remained "quite a few other issues" to be worked out. He did not specify what those were.