The US wants and expects more from Pakistan in the fight against insurgents and is ready to offer additional assistance if Islamabad asks, two senior Obama administration officials said.

'We've gotten more cooperation and it's been a real sea change in the commitment we've seen from the Pakistan government. (But) we want more. We expect more,' Secretary of State Hillary Clinton told CBS' '60 Minutes' in an interview, excerpts of which were released on Friday.

She added that Washington had also warned of 'severe consequences' if a successful attack in America were traced back to Pakistan. She did not elaborate.

Investigations into the Pakistani-American suspect in last Saturday's failed bombing attempt in New York's Times Square have uncovered possible links to the Pakistani Taliban and a Kashmiri Islamist group.

That has prompted speculation the US, Pakistan's top provider of aid, could press Islamabad to open risky new fronts against Islamic militants.

But Defense Secretary Robert Gates, speaking to reporters on a trip to Kansas, appeared to play down the chances of an expanded Pakistani crackdown on insurgents.

He pointed to the strain on security forces already battling militants in tribal areas bordering Afghanistan.

'With their military operations in the west, they've started to be pretty thinly stretched themselves, as well as taking a substantial number of casualties,' Gates said.

The US was ready to step up assistance to Pakistan, he said.

'We're willing to do as much ... as they are willing to accept,' Gates said. 'We are prepared to do training, and exercise with them. How big that operation becomes is really up to them.'

Double game

Citing anti-American sentiment in Pakistan, Gates added, 'They (Pakistani leaders) are also very interested in keeping our footprints as small as possible, at least for now.'

President Barack Obama's administration has repeatedly praised Pakistani military operations over the past year, including the recent capture in Pakistan of the Afghan Taliban's No. 2, Mullah Abdul Ghani Baradar.

Clinton said it marked an improvement from the 'double game going on in the previous years, where we got a lot of lip service but very little produced.'

'We have seen the killing or capturing of a great number of the leadership of significant terrorist groups and we're going (to) continue that,' she said.

The US, which sees Pakistan's effort against militants as crucial to its fight against the Taliban in Afghanistan, has about 200 military personnel in Pakistan, including Special Operations forces on a training mission.

The CIA is also waging a covert war using pilotless drone aircraft to target insurgents in Pakistan.

'I think cooperation has continued to (improve), the relationship is continuing to improve, and I think we just keep moving in that direction,' Gates said.

A White House official said the US had been working with Pakistan and would keep assisting a Pakistani offensive to root out the Taliban.

'We've been working on the other side of the border, of course, with Pakistan in developing a strong partnership in which they have gone on the offensive -- the largest offensive they've undertaken in some years -- in order to root out extremists within their borders, including the Taliban,' deputy national security adviser Ben Rhodes told reporters. – Reuters