"We want to make certain that no terrorist organisation can find a haven anywhere, and, with a border adjoining Afghanistan, that makes Pakistan a priority," Mattis said.
United States resident Barack Obama on Tuesday told his Afghan counterpart Hamid Karzai that America might pull all of its troops out of the war-ravaged country by the year end, but did not rule out the possibility of an agreement on a "limited" post-2014 mission.
Jim Mattis in his resignation letter to the US president wrote that he deserved a defence secretary whose views were better aligned with his on these and other subjects.