US probe on Pakistan attack due by December 23

US-led investigators were on Tuesday given until December 23 to probe a Nato air strike killing Pakistani soldiers, threatening to prolong significantly Pakistan's blockade on Nato supplies into Afghanistan.

The US military appointed Brigadier General Stephen Clark, a one-star air force general based in Florida, to lead the investigation into the attack, which has further shaken already fragile relations between the US and Pakistan.

The team, set to include a Nato representative, is yet to arrive in Afghanistan but an initial military assessment team went to the border at the weekend after Saturday's catastrophic strike killing 24 Pakistani troops.

The Afghan and Pakistani governments are also being invited to take part. There was no immediate reaction from Islamabad or Kabul, although some analysts voiced surprise that it will take as long as nearly four weeks.

A Western military official in Kabul, speaking on condition of anonymity, said it was not unusual for US Central Command to carry out such investigations although Nato generally undertakes probes into civilian casualties.

The source added that the schedule for the findings being delivered was "way quicker" than initially expected.

The killings are the latest crisis to plunge US-Pakistani ties into free fall and raise disturbing questions over loyalties in the 10-year war against the Taliban and the extent to which the two allies cooperate with each other.

Islamabad insists that the air strikes were unprovoked, but Afghan and Western officials have reportedly accused Pakistani forces of firing first.

"With the kind of technology available to the US and Nato, it was expected they would be able to do it (the investigation) much earlier, not more than two weeks," Pakistani defence analyst Talat Masood told AFP.

"To reopen the border, there has to be some assurance from the top US leadership," he added. "Maybe after such an assurance, the border will be opened or limited supplies allowed (to cross)."

In Pakistan, angry protests over the Nato strikes pushed into a fourth day, with 150-200 people demonstrating in Pakistani-administered Kashmir, setting fire to an American flag and an effigy of Nato chief Anders Fogh Rasmussen.

The crowd carried banners and shouted: "Those who befriend America are traitors" and "We are ready for Jihad", an AFP reporter said.

Pakistan has vowed no more "business as usual" with the United States, shutting its Afghan border to Nato convoys, ordering Americans to vacate an air base reportedly used by CIA drones and a review of the alliance.

Yet behind the rhetoric, Islamabad has little wriggle room, being dependent on US aid dollars and fearful of the repercussions for regional security as American troops wind down their presence in Afghanistan in the coming years.

In an interview with CNN, Prime Minister Yousuf Raza Gilani stopped short of threatening to break the alliance altogether saying: "That can continue on mutual respect and mutual interest."

US officials, who spoke on condition of anonymity, said the Obama administration was working on a response to a number of demands from Pakistan but said they do not anticipate significant changes in the relationship.

White House spokesman Jay Carney said President Barack Obama believed Saturday's incident was "a tragedy", and said Washington valued what he called an "important cooperative relationship that is also very complicated".

Last time Pakistan closed the border, in September 2010 after up to three soldiers were killed in a similar cross-border raid, it only reopened the route after the United States issued a full apology.

The US military has insisted the war effort in Afghanistan would continue and has sought to minimise the disruption to regular supply lines.

Nearly half of all cargo bound for Nato-led troops runs through Pakistan. Roughly 140,000 foreign troops, including about 97,000 American forces, rely on supplies from the outside to fight the ten-year-old war in Afghanistan.

The United States also depends on Islamabad's tacit cooperation over an intense campaign of CIA drone strikes on Taliban and Al-Qaeda operatives.

Even if the Pakistanis make good on their threat over the Shamsi air base, US officials and analysts say it would be largely symbolic as Washington could fly Predator and Reaper drones out of neighbouring Afghanistan.

Pakistan had earlier asked the US to vacate the remote air base in the country's southwest.

"The real issue isn't Shamsi, it's air space," a senior US official told AFP on condition of anonymity. And so far, officials say there has been no sign that Islamabad would bar the US aircraft from flying over Pakistan.

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