The cables released by WikiLeaks said that US special operations forces were embedded with Pakistani troops for intelligence gathering by the summer of 2009 and deployed with them on joint operations in Pakistani territory by September the same year.
The issue has gained heightened sensitivity in the wake of the US raid against Osama bin Laden in Abbottabad.
The revelations go against the Pakistani military's claim that it will not allow foreign troops to operate within the country for operations to flush out the Taliban and other militant elements.
"We have created Intelligence Fusion cells with embedded US Special Forces with both SSG and Frontier Corps (Bala Hisar, Peshawar) with the Rover equipment ready to deploy," then US Ambassador Anne Patterson was quoted by Dawn newspaper as saying in a cable to the State Department in May 2009.
"Through these embeds, we are assisting the Pakistanis collect and coordinate existing intelligence assets," she said.
At the time, Patterson noted that the US had "not been given Pakistani military permission to accompany the Pakistani forces on deployments as yet." By September, plans for joint intelligence activities had been expanded to include army headquarters.
"Pakistan has begun to accept intelligence, surveillance, and reconnaissance support from the US military for (counter-insurgency) operations," Patterson wrote.
"In addition... intelligence fusion centers" had been established "at the headquarters of Frontier Corps and the 11th Corps and we expect at additional sites, including GHQ and the 12th Corps in Balochistan", she said.
In April 2009, the cell at Bala Hisar assisted the Pakistan military operation then taking place in Lower Dir district of Khyber-Pakhtunkhwa province.
"US Special Operations Command Force are assisting the FC at the Intelligence Fusion Cell at FC Headquarters with imagery, target packages, and operational planning," a cable from that month said.
A number of leaked cables reveal that the US was eager to embed American troops with Pakistanis soldiers.
"On a brighter note, there is the possibility that operations in the northern FATA may provide additional opportunities to embed US Special Operations Forces with FC units to provide ISR (intelligence, surveillance and reconnaissance) support and general operational guidance," Patterson wrote in a November 2009 cable.