PESHAWAR, Pakistan - Militants in northwest Pakistan blew up a tanker truck 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 the 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 nonlethal supplies for Western troops in Afghanistan through Pakistan - a threat that could grow more acute after 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, which 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 the blaze seemed under control, people tried to take the fuel. A secondary blast killed 15 and wounded one, Khan said.

The 14 tankers damaged in the other bombing were parked at Torkham, a town along the Pakistan-Afghan border where there have been 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 United States 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.-Pakistani relations are at a low point over the unilateral May 2 American raid that killed bin Laden in the 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-Qaeda chief was hiding in the area.

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.