The United States on Friday said that Pakistani leaders must take action against rapidly expanding Taliban [Images] militants who now pose an 'existential threat' to Islamabad [Images].

"I think that some of the leaders certainly understand that (threat posed by the Taliban), but it is important that they not only recognise it but take the appropriate actions to deal with it," United States Defence Secretary Robert Gates told reporters during his visit to Camp Lejeune in North Carolina.

When referred to news reports that Taliban has now moved beyond the Swat Valley, he said, "My hope is that there will be an increasing recognition on the part of the Pakistani government that the Taliban in Pakistan are in fact an existential threat to the democratic government of that country."

"The stability and the longevity of the democratic government in Pakistan is central to the efforts of the coalition in Afghanistan and it is also central to our future partnership with the government in Islamabad," Gates said.

"We want to support them. We want to be helpful in any way we can. But it is important that they recognise the real threats to their country," he added.

The advances of Taliban, which moved to about 100 km of Islamabad by taking control of Burner district, has stunned the US, as reflected in the strong remarks of Secretary of State Hillary Clinton [Images], who also said it posed an 'existential threat' to Pakistan.