Washington, Mar. 28 : The US special envoy to Pakistan and Afghanistan Richard Holbrook has said that the insurgency in Pakistan along the Afghan border is the most daunting situation that the US is facing presently.

Talking to media persons right after President Barack Obama unveiled a new policy for Afghanistan, Holbrooke said that the US is very concerned about dealing with the problem on the western border of Pakistan.

"And our superiors would all freely admit that of all the dilemmas and challenges we face, that is going to be the most daunting," The Dawn quoted Holbrook, as saying.

He said the US is facing constraints of Islamabad's `red line' policy, which is certainly preventing it from taking major action against the outlawed terror groups operating from Pakistani soil.

"The red line is unambiguous and stated publicly by the Pakistani government `no foreign troops on our soil'," he said.

When enquired about the Obama Administration's decision to continue the drone strikes on milltant hideouts inside Pakistan, Holbrooke said it would be not be appropriate to disclose the issue, as it could endanger future military operations in the region.

While the United States claims that the Predator drone strikes in the ungoverned tribal region along the Pakistan-Afghanistan border have been successful with scores of top Taliban and Al-Qaeda leaders being killed, Pakistan, on number of occasion has opposed the missile hits saying it is proving counterproductive in the `war on terror', besides killing innocent civilians. (ANI)