Washington, Apr 28 : US Chairman of the Joint Chiefs of Staff Admiral Michael Mullen is frustrated particularly by the Pakistani political leadership's inability to confront the extremist threat, and remains "very alarmed by the growing Taliban threat in the country," his spokesman has said.

Mullen has made two visits to Pakistan in less than three weeks and is "deeply alarmed by what he has found," his spokesman, Captain John Kirby told CNN.

"It is a very precarious security situation." Mullen is particularly "alarmed by what is going on in the Swat Valley," Kirby said.

"Instead of laying down their arms under the terms of a peace deal, the Taliban picked them up," The Nation quoted Kirby, as saying.

Mullen is making his views known after returning from his 11th visit to Islamabad over the weekend.

Kirby said the chairman's views about the deterioration in Pakistan have accelerated since he visited Islamabad in early April with special envoy Richard Holbrooke.

During the most recent visit Mullen "expressed those concerns," and urged Pakistani military leaders to "be more aggressive in confronting" the Taliban, Kirby said.

Mullen also reiterated the US offer of any military assistance that the Pakistanis find acceptable; although that does not include US ground troops.

A senior US military official said that there is growing worry there are parts of Pakistan's North-West Frontier Province that appear to be under the Taliban control and that the Taliban strategy is to maintain governance in those areas.

The US military thinks Pakistan's nuclear weapons remain in safe hands, Kirby said. (ANI)