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.
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.
North Korea has carried out several nuclear tests and experts predict more could be in the offing as it moves closer towards developing a nuclear warhead that could reach the US.
On Wednesday, it test-fired a medium-range ballistic missile from its eastern port of Sinpo into the Sea of Japan. That test came a month after four ballistic missiles were fired towards the Sea of Japan, moves that provoked a furious reaction by Japan.
On its part, North Korea says it is provoked by military exercises between the US and South Korea, which it sees as preparation for an invasion.
North Korea has also been closely watching how US President Donald Trump has been responding in Syria.
Early on Friday, the US military launched air strikes against the Syrian government, in retaliation for a reported chemical attack.
North Korea called it an “intolerable act of aggression against a sovereign state”, and said the strike showed it was justified in bolstering its own defences.
The most recent test – condemned by Japan and South Korea – came on the eve of a visit by China’s President Xi Jinping to the US to meet President Trump.
The two leaders discussed how to rein in North Korea’s nuclear and missile programmes as the US steps up the pressure on China, a historic ally of Pyongyang, to help reduce tension.
China has long been North Korea’s closest diplomatic ally and trading partner, but the relationship has become increasingly strained over Pyongyang’s refusal to halt nuclear and missile testing.
Mr Trump said in a recent interview that Washington was ready to act without Beijing’s co-operation: “If China is not going to solve North Korea, we will.”