Jim Mattis has announced his resignation citing policy differences with his president. He was seen as a stabilizing force for an international order in the chaotic, go-it-alone administration.

U.S. Defense Secretary Jim Mattis said that the U.S. military's competitive edge has eroded "in every domain of warfare" and blamed that partly on spending caps and congressional budget dysfunction.

Speaking on a military plane en route to Cairo, U.S. Defense Secretary Jim Mattis told reporters that as offensive operations against Islamic State in Syria entered their final stages, he expected the focus to move towards holding territory instead of arming Syrian Kurdish fighters.

U.S. Defense Secretary Jim Mattis says he cannot imagine the United States ever accepting a nuclear North Korea, warning that its rapidly advancing nuclear and missile programs would undermine, not strengthen, its security.

South Korea's defence ministry holds a welcome ceremony for U.S. Defense Secretary Jim Mattis.

U.S. Defense Secretary Jim Mattis on Wednesday praised Filipino soldiers for defeating pro-Islamic State militants in a five-month battle in Marawi City, the southern Philippines and said there were no credible allegations of human rights violations.

U.S. Defense Secretary Jim Mattis said on Thursday the U.S. military did not have all the accurate information on an ambush in Niger earlier this month that killed four U.S. soldiers.

U.S. Secretary of Defense Jim Mattis seeks to reassure Ukrainian President Petro Poroshenko of Washington's support, but stops short of committing to lethal weapons aid.

President Donald Trump has a made a decision on the United States' strategy for Afghanistan after a "sufficiently rigorous" review process, Defense Secretary Jim Mattis said on Sunday.

U.S. President Donald Trump has given Defense Secretary Jim Mattis the authority to set troop levels in Afghanistan, a decision opening the door to future troop increases requested by the top American commander.

Pentagon chief Jim Mattis delivers a somber caution on North Korea, saying any military attempts to resolve the crisis would be "tragic on an unbelievable scale."

U.S. Defence Secretary Jim Mattis says he does not see any need for dramatic military moves in the South China Sea to contend with China's assertive behaviour after a meeting with his Japanese counterpart in Tokyo.