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Militants in northwest Pakistan blew up a tanker carrying oil for NATO forces in Afghanistan on Saturday, and a secondary explosion killed 15 people as a group gathered to try to siphon off some of its fuel. Another bombing damaged 14 NATO tankers in a nearby border town, but no one was hurt.

A Pakistani Taliban group claimed responsibility for both attacks, underscoring the threat to vehicles that carry non-lethal supplies for Western troops in Afghanistan through Pakistan — a threat that could grow more acute in the wake of the U.S. killing of Osama bin Laden in northwest Pakistan.

The explosions coincided with the publication of leaked U.S. diplomatic cables indicating that U.S. Special Forces provided intelligence and other assistance to the Pakistani army as it fought Taliban forces in 2009. It was the latest evidence that the U.S. troops did more than just train Pakistanis, as was publicly claimed.

The explosions occurred overnight in Pakistan's Khyber tribal region, an area that numerous trucks carrying supplies for U.S. and NATO forces in Afghanistan must traverse, local administrator Abdul Nabi Khan said.

In the Landi Kotal area of Khyber, a tanker caught fire after a bomb blast. Once it seemed the blaze was controlled, people tried to take the tanker's fuel. Another blast then occurred, killing 15 people and wounding one, Khan said.

The 14 tankers damaged in the other bombing were parked at Torkham, a town along the Pakistan-Afghan border. Torkham has witnessed many attacks on the U.S.-NATO supply line.

A man who claimed to be a spokesman for the Abdullah Azzam Brigade, a Taliban group, called journalists in the northwest city of Peshawar to say the group was behind the attacks. The goal was to stop the U.S. from launching more missile strikes in Pakistan's northwest, said the man, who declined to give his name in line with his group's policy.

U.S. and NATO commanders insist the attacks in Pakistan barely affect their operations. But in recent years, the military units have tried to reduce their dependence on Pakistan routes, increasingly using roads running through Central Asian countries and relying on supplies to be flown in.

U.S.-Pakistani relations are at a low point over the unilateral May 2 American raid that killed bin Laden in the northwest Pakistani garrison city of Abbottabad. Pakistan is angry that it was not told in advance of the raid and says it did not know the al-Qaida chief was hiding in the area.

In the wake of the raid, Pakistan's parliament has demanded that the U.S. stop its missile strikes, and warned that the government may cut off the supply route altogether if the strikes don't end. On Saturday in Karachi, around 5,000 Pakistanis led by former cricketer-turned-politician Imran Khan protested the missile strikes.

But there have been multiple missile strikes since the bin Laden slaying, a sign that the U.S. is unwilling to abandon what it considers a highly effective weapon against insurgents that hide in Pakistan and threaten Western troops in Afghanistan.

Pakistani leaders' positions on the missile strikes and other U.S. involvement in the region are murky, with growing evidence that officials condemn any such "violations of sovereignty" in public while privately backing them.

The newly published U.S. diplomatic cables appear to support that.

The cables were obtained through the Wikileaks organization and published by Dawn, a respected English-language newspaper in Pakistan. Several of the cables were written by Anne Patterson, then the U.S. ambassador to Pakistan.

The cables indicate that U.S. troops joined Pakistani forces for the purposes of intelligence, reconnaissance support and surveillance during 2009, a year when Pakistan was involved in multiple offensives in its northwest, pockets of which were under the control of various Taliban factions.

This year, officials have said the U.S. presence in Pakistan has been scaled back, and joint operations suspended. Some of the chill is related to the bin Laden raid, but some of it dates to January, when an American CIA contractor shot dead two Pakistanis he said were trying to rob him. The incident angered the Pakistani army, but the American was freed after his victims' relatives accepted compensation.

The U.S. cables referred to some of the sites where the cooperation occurred as "fusion centers." In April 2009, for instance, there was U.S. involvement in intelligence gathering for the Pakistani military operation in Lower Dir, which preceded a major offensive in the Swat Valley.

The U.S. appeared keen on increasing its involvement to include assistance on the ground in battle zones.

The cables included apparent references to at least one case in which U.S. troops did provide assistance in a conflict zone, that of the Pakistani operation in Bajur tribal region in fall 2009.

That instance has previously been referenced in media reports about earlier cables released through Wikileaks. Those reports also described small U.S. troop deployments in South Waziristan and North Waziristan, where the Americans offered intelligence, surveillance and other assistance, including coordinating U.S. missile strikes.

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Associated Press Writer Nahal Toosi in Islamabad and Mohammad Farooq in Karachi contributed to this report.