BBC: The US is moving an advanced missile system to the Pacific island of Guam as a precaution following threats by North Korea, the Pentagon has said.
The Department of Defence said it would deploy the ballistic Terminal High Altitude Area Defense System (Thaad) in the coming weeks.
Pyongyang has threatened to target South Korea and the US in recent weeks.
The state's warlike rhetoric follows new UN sanctions and joint military drills by the US and South Korea.
The Thaad system includes a truck-mounted launcher, interceptor missiles, and AN/TPY-2 tracking radar, together with an integrated fire control system.
The Pentagon said in a statement the missile system would be moved to Guam as a "precautionary move to strengthen our regional defense posture against the North Korean regional ballistic missile threat".
"The United States remains vigilant in the face of North Korean provocations and stands ready to defend US territory, our allies, and our national interests," the statement added.