The US military has ordered a navy strike group to move towards the Korean peninsula, amid growing concerns about North Korea's missile programme.
The Carl Vinson Strike Group comprises an aircraft carrier and other warships.
US Pacific Command described the deployment - now heading towards the western Pacific - as a prudent measure to maintain readiness in the region.
President Trump has said the US is prepared to act alone to deal with the nuclear threat from North Korea.
"The number one threat in the region continues to be North Korea, due to its reckless, irresponsible and destabilising programme of missile tests and pursuit of a nuclear weapons capability," US Pacific Command spokesman Dave Benham said.
The strike group comprises the Nimitz-class aircraft carrier USS Carl Vinson, two guided-missile destroyers and a guided-missile cruiser.
As well as massive striking power, the carrier group - headed by Admiral Nora Tyson - has the capability to intercept ballistic missiles.
It was originally due to make port calls in Australia but instead has been diverted from Singapore to the west Pacific - where it recently conducted exercises with the South Korean Navy.(Source: BBC)