Suspected militants in Pakistan set fire to three dozen tankers carrying fuel for NATO troops in Afghanistan on Friday, officials said, a day after three soldiers were killed in a cross-border NATO air strike.
Angered by repeated incursions by NATO helicopters over the past week, Pakistan has blocked a supply route for coalition troops in Afghanistan.
Pakistan is a crucial ally for the United States in its efforts to stabilize Afghanistan, but analysts say border incursions and disruptions in NATO supplies underline growing tensions in the relationship.
A senior Pakistani intelligence official said the border incursions could lead to a "total snapping of relations." But U.S. special envoy Richard Holbrooke told a forum in Washington the current tensions were unlikely to "change the fundamental relationship between our two countries."
Senior local officials blamed "extremists" for the attack on the tankers in the southern town of Shikarpur. About 12 people, their faces covered, opened fire with small arms into the air to scare away the drivers and then set fire to 35 tankers.
"Some of them have been completely destroyed and others partially. But there is no loss of human life," Shikarpur police chief Abdul Hameed Khoso told Reuters.
In a separate incident, two unidentified men fired on a NATO tanker traveling through a town in Pakistan's southwestern Baluchistan province toward Afghanistan. Two people burned to death after the vehicle caught fire, security officials said.
Police arrested 10 people after the earlier attack, including five netted from a raid on an Islamic seminary, or madrasa.
The tankers were parked at a filling station on their way to Afghanistan from Pakistan's southern port city of Karachi.
Thursday, three Pakistani soldiers were killed and three wounded in two cross-border incursions by NATO forces chasing militants in Pakistan's northwestern Kurram region.
It was the third cross-border incident in a week, the Pakistan military said. NATO said the helicopters briefly crossed into Pakistan airspace after coming under fire from people there.
Other options?
Prime Minister Yusuf Raza Gilani, speaking in parliament, said Pakistan was a partner in the war against Islamist militancy, but would allow no infringement of its sovereignty.
"I want to assure the entire nation from this house that we will consider other options if there is interference in the sovereignty of our country," Gilani said without elaborating.
Pakistan's ambassador to Belgium lodged a protest with NATO's deputy general secretary over the incursions, the Pakistan embassy said in a statement.
Holbrooke, the U.S. special representative for Afghanistan and Pakistan, told the Washington Ideas Forum the border incident was "very unfortunate" and that the NATO secretary general had expressed his regrets, which Holbrooke echoed.
Despite tensions, analysts say a rift is unlikely between Pakistan and its Western allies as each side needs the other.
The European Union said it had decided to more than double its Pakistan flood aid to 150 million euros ($205 million).
Thursday, hours after the cross-border attack, Pakistani authorities halted tankers carrying supplies for the NATO forces passing through the Khyber tribal region on the Afghan border.
About three-quarters of the cargo for NATO forces in Afghanistan moves through Pakistan, mostly via two border crossings: Chaman north of Quetta in Baluchistan and Torkham at the Khyber Pass.
Another third flows into Afghanistan through the northern distribution network across Kazakhstan and Uzbekistan. Sensitive gear like ammunition, weapons and critical equipment is flown in.
Officials say supplies through Chaman continue uninterrupted.
Holbrooke said it was "inconceivable" that border crossings in the Khyber region would face any long closure because of the "colossal effect" it would have on the surrounding area.
Pakistan under spotlight
Pakistan has again come under the spotlight after Western intelligence sources said a plot to stage attacks in Europe had been disrupted by an upsurge in missile strikes by U.S. drones.
Security officials said they had no evidence of a plot being hatched in Pakistan's tribal areas. Most recent drone strikes have taken place in the northwestern North Waziristan region.
"It's no secret that there are terrorists from all nationalities in North Waziristan. They are Arabs, Uzbeks, Pakistani, Afghan, Chechans, German, Brits, Americans, everyone. And they are threat to us, to their own countries and to the entire world," a senior security official said.
"But to say that we have any specific information that they were plotting attacks against this country or that country, then sir, we don't have any concrete information or intelligence about that."