jim mattis
US Secretary of Defense Jim MattisMark Wilson/Getty Images

Asserting that 40 years is enough for every responsible nation to get on board with the south Asia peace process, US Defence Secretary Jim Mattis, in a strong message to Pakistan, said it is time for everyone to support the efforts of the UN, Prime Minister Narendra Modi and Afghanistan in this regard.

"We're looking for every responsible nation to support peace in the sub-continent and across this war in Afghanistan that's gone on now for 40 years," he told reporters at the Pentagon on Monday as he welcomed Union Defence Minister Nirmala Sitharaman for talks.

"It's time for everyone to get on board, support the United Nations; support Prime Minister Modi's, (Afghan) President (Ashraf) Ghani and all those who are trying to maintain peace and make for a better world here," Jim Mattis said.

"We are on that track. It is diplomatically led as it should be, and we'll do our best to protect the Afghan people," he added.

Mattis was responding to a question from reporters about the letter written by US President Donald Trump to Pakistan Prime Minister Imran Khan, seeking his support in the peace process in Afghanistan. In his letter, Donald Trump has made it clear that Pakistan's full support in this regard "is fundamental" to building an enduring US-Pakistan partnership.