New Delhi: US Defence Secretary Jim Mattis has asserted that President Donald Trump would try to work with Pakistan "one more time" but is prepared to take "whatever steps necessary" if Islamabad does not "change its behaviour" and continued to support terror groups.

Mattis also warned Pakistan of global "diplomatic isolation" and losing its Non-NATO ally status if it failed to dismantle terrorists' safe havens on its soil.

His tough talk on Pakistan came at a time when Foreign Minister Khwaja Asif is in the US as part of efforts to rebuild bilateral ties frayed after President Trump accused Islamabad of sheltering terror groups.

"If our best efforts fail, President Trump is prepared to take whatever steps necessary," Mattis told members of the powerful House Armed Services Committee during a Congressional testimony on South Asia and Afghanistan yesterday.

He was asked a series of questions by Congressmen who expressed their frustration on Pakistan not taking actions against terror groups.

Without much elaboration, Mattis said the US has "enormously powerful number of options" if Pakistan does not follow through and be a better promoter of stability in the region.

"Right now, I would like to think we will be successful," Mattis said. "With the growing consensus against terrorism, they'll find themselves diplomatically isolated," he added.

"There is an awful lot of advantage to Pakistan of coming online with the international community, and we have to stay focused there, but the penalties are just as significant as the advantages if they choose to go a different direction," he said.

"But for right now, the US needs to try one more time to make this strategy work with them by, with, and through the Pakistanis," he said, referring to the new Afghan policy.

When Congressman Rick Larsen asked if revocation of non- NATO allies status is on the list of possibilities against Pakistan, Mattis said, "I'm sure it will be." 

President Trump announced his Afghanistan and South Asia policy in August in which he adopted a tough policy against Pakistan.

In a meeting with the Secretary of State Rex Tillerson, Asif defended his country's role in the war against terrorism.

He claimed that Pakistan has pursued a zero-tolerance and indiscriminate approach in its campaign against all terrorist and militant groups.

However, Mattis told lawmakers that while the US is adopting "a whole of government approach" on Pakistan, it is also aligning NATO countries on this.

"What you're going to see is 39 nations all in the NATO campaign working together to lay out what it is we need Pakistan to do, he said.