The trucks had halted overnight in the town of Shikarpur en route to the only border crossing into Afghanistan that remains open following Pakistan's closure of the Khyber Pass to NATO suppliers Thursday morning. Trucks had only recently started to pass through Shikarpur when a road was reopened that had been washed out by floods this summer.
The incident encapsulates many of the challenges for the NATO supply lines, including militant attacks, disastrous floods, and mercurial Pakistan-US relations. While the level of disruption at the moment remains manageable, further problems could spell trouble.
"If these attacks become frequent and they begin to take a heavy toll on the supply lines then I think it could be a huge source of worry to NATO forces. As the Americans increase their numbers they become ever more dependent on this stable route through Pakistan," says Rifaat Hussein, a strategic analyst at Quaid-i-Azam University in Islamabad.
Pakistan closed the Khyber Pass border crossing following several recent border incursions by NATO forces. The latest incident on Thursday morning involved US helicopters destroying a Pakistani border post, killing three paramilitary troops with the Frontier Corps. Pakistan claims its forces fired warning shots over the incursion.
"You fire at a helicopter in a combat zone, they usually take that as hostile and return fire," said Pentagon spokesman Col. Dave Lapan.
US-Pakistan relations have sunk rapidly despite recent goodwill surrounding flood relief. America provided $362 million in assistance and sent helicopters and crews to rescue survivors.
But as frequently happens, says Dr. Hussein, one positive step forward in the US-Pakistan relationship was followed by several steps back. Among them: dozens of drone attacks this month, violations of Pakistan's airspace, and criticism from US Secretary of State Hillary Clinton about the lack of taxation in Pakistan. He says that assaults on NATO trucks are often revenge attacks for drone strikes.
Supply routes limited
In the bigger picture, says Ijaz Khattak, a professor of international relations at Peshawar University, Pakistan is also not supportive of the US surge in Afghanistan. That's because if it were to work it could put Islamabad in a less central position during peace negotiations.
"You see on the one side an increase in American pressure, and in Pakistan an increase in different tactics to make it difficult for the US to carry on with its so-called surge policy Afghanistan," says Professor Khattak.
Some 80 percent of the fuel and other nonlethal supplies for the war effort travel through Pakistan, according to the Associated Press. In recent years, the coalition has added redundancy to its supply lines by opening several supply routes through the Central Asian republics as well.
Those new routes are more expensive, but the various squeezes within Pakistan are no doubt raising costs there as well.
Attackers drove Land Cruisers
The torched tankers had been parked for the night at a gas station, says local district coordination officer Saeed Ahmed Mangnejo. No one was hurt in the attack, he says, and he declined to speculate on who was responsible.
"It is a bit early to say, an investigation is under way," he says. "No militants are operating in this area. This is a peaceful area."
Rehmatullah Soomro, a reporter for the newspaper Dawn who interviewed some of the drivers, says they told him they were headed to Kandahar. The attack took place at about 1:30 a.m. Mr. Soomro says few witnessed the attack but some say the attackers came in Toyota Land Cruisers and used rocket launchers.
Trucks ferrying NATO supplies through Shikarpur are all headed toward Kandahar; trucks headed to Kabul through the Khyber Pass go a different route, says Mr. Mangnejo. But, he says, trucks had not been seen around town for weeks until two days ago when a road connecting Shikarpur was fixed.
While the floods caused rerouting of trucks heading to Kandahar, the trucks heading to Kabul seem less disrupted.
Interviews with Pakistani truckers in Kabul last week indicated that the floods did not force any major rerouting of lorries heading through Pakistan's northwestern province of Khyber-Pakhtunwa. Drivers showed cellphone videos of widespread damage to their villages, but they said the road network for trucks remained intact.
Issam Ahmed contributed reporting from Islamabad, Pakistan.