He said that the Trump administration believes that it would be highly difficult to sustain any stabilisation in South Asia, not just in Afghanistan, but certainly anywhere around Pakistan and India unless safe havens are removed.

Mattis was responding to questions from lawmakers who wanted to know why the administration believes that Pakistan will change its behaviour this time.

Trump has said that he would change the US approach to Pakistan, which continues to harbour militants and terrorists who target US service members and officials, said Senator John McCain, Chairman of the Senate Armed Services Committee.

“But we still do not know what specific steps the United States will take to convince or compel Pakistan to change its behaviour, or what costs we will impose if Pakistan fails to do so,” McCain said.

Indeed, McCain said it is unclear to him if the administration believes any step or series of steps the United States might take will lead Pakistan to cease its support and sanctuary for certain terrorist groups, which has been a "feature of" its national security policy for decades.