The Pentagon says there are actually 11,000 U.S. troops in Afghanistan, 2,600 more than were previously said to be there.
Mattis hinted that the U.S. could send defensive weapons to Ukraine.
Soldiers, security experts, diplomats and right-wing outlet Breitbart pan president's plan for Afghanistan.
Asked about Trump's latest comments, Secretary of Defense Jim Mattis instead emphasized the importance of diplomatic efforts.
Senator Claire McCaskill demanded to know why the military approved $50 million in irregular spending on luxury cars and significant other's salaries, calling it a "slap in the face" to taxpayers.
North Korea claims it's not scared of President Donald Trump or his "old warmonger" Secretary of Defense James Mattis.
More than 64 years after the CIA helped overthrow Iran's democratically elected government, the country reacted to recent U.S. comments on regime change.
The deal was inked after Trump accused Qatar of being a "high-level" sponsor of terrorism.
Pyongyang's stepping up of missile and nuclear programs put North Korea at top of national security agenda, says the U.S. Defense Secretary.
The U.S. has said it will not attend Moscow-led peace talks scheduled for Friday.
Vice president seemingly contradicts Trump at Munich conference, as the president has been critical of the alliance.
Mattis said the U.S. should ensure its diplomats "negotiate from a position of strength."
Trump's contradictory remarks on NATO, calling it "obsolete" during the U.S. election campaign but also supporting it, as well as his praise for Russian President Vladimir Putin, have deeply unsettled allies who fear for transatlantic ties.
Hillary Clinton's lead in the popular vote now exceeds 2.5 million.
Mattis is a revered figure in the Marine Corps and known for his distrust of Iran.