According to sources, McMaster met with officials from South Korea and Japan.
Global Hot Spots
The U.S. faces new challenges in Iraq and Syria despite the crumbling of ISIS.
The U.S. Air Force is deploying six B-52H Stratofortress bombers and 300 airmen from Barksdale AFB.
Japan's public broadcaster mistakenly sent an alert Tuesday warning citizens of a North Korean missile launch.
Secretary of State Rex Tillerson huddles Tuesday with nations that fought on America's side in the Korean War.
An Islamic State group offshoot is claiming it carried out the October attack in Niger that killed four U.S. soldiers.
The Russian military is conducting massive drills involving truck-mounted intercontinental ballistic missile launchers.
Bashar al-Assad's army objects to any form of U.S. presence in the country and will seek to put an end to it.
The Russian foreign minister said the U.S. doesn't want to recognize "the reality of the emerging multipolar world."
The Pentagon's senior enlisted member has drawn the line against ISIS: "surrender or die!"