Pakistan has signed a deal with the United States governing arrangements for NATO convoys travelling to Afghanistan.
Under the agreement inked in Rawalpindi on Tuesday, the home of Pakistan's powerful military, the United States will release $1.1bn under the Coalition Support Fund to reimburse the troubled nation for battling fighters within its borders.
The deal codified a largely informal arrangement that has allowed the US to contract trucks to ship goods destined for the US-led NATO military effort in Afghanistan through Pakistan over the past decade.
Pakistan pushed for a written pact in drawn-out negotiations that led to the supply line's reopening in early July following a seven-month blockade in retaliation for American air strikes across the Afghan border.
Islamabad agreed to reopen land routes for NATO goods on July 3 after the longest border closure of the decade-long war in Afghanistan - in protest at botched US air raids that killed 24 Pakistani troops last November.
A few trucks made it across even before the agreement, which is part of efforts by the uneasy allies to patch up their fractious relationship.
Relations between the two countries plunged into crisis last year over the air strikes and the US raid that killed al-Qaeda leader Osama bin Laden, who was in hiding in the Pakistani city of Abbottabad.
The agreement comes just a day before the head of Pakistani intelligence, Lieutenant General Zaheer ul-Islam, begins a three-day visit to Washington for talks with the head of the CIA, which has been interpreted as another sign of a gradual rapprochement.
Officials at the ceremony in Rawalpindi gave no details of the Memorandum of Understanding nor did they release a copy at a news conference.
Guidelines laid out by the Pakistani parliament earlier this year insisted that in future no weapons and ammunition be transported through the country, though Western officials say this never happened in the first place.
A Pakistani security official said the agreement gave Islamabad the right to refuse or reject any shipment, and that special radio chips would be fitted to containers for monitoring.
Richard Hoagland, the deputy US ambassador to Islamabad who signed the agreement on behalf of Washington, hailed it as a "demonstration of increased transparency and openness" between the two governments.
Pakistan lifted its blockade after US Secretary of State Hillary Clinton apologised for the air raid deaths, but a row over security guarantees and compensation have delayed a resumption of normal traffic.
Officials closed the Torkham border crossing, the quickest route to Kabul from the port city of Karachi, to NATO traffic on Thursday over security fears.
The Pakistani Taliban have vowed to attack NATO supplies and last Tuesday, one of the truck drivers was shot dead in the northwestern town of Jamrud.
Asif Yasin Malik, the Pakistani defence secretary, said the deal would contribute to the stability of the region and hailed it as a "landmark event".
In Karachi, a leading subcontractor in the business, Alhaj Taj Mohammad, said Tuesday's agreement could help resolve the rows over security and compensation but predicted it could still take 10 days to start clearing goods from customs.
"This agreement is very important, we were waiting for it," Mohammad told AFP. "Hopefully we'll have a copy by this evening after which things could speed up," he added.
But Akram Khan Durrani, chairman of the All Pakistan Oil Tankers Owners Association, said fears about security would remain.
"No owner is going to move his vehicle until solid guarantees are given for it," he said.