A United States Navy strike group is moving towards the western Pacific Ocean near the Korean Peninsula as a show of force amid growing concerns about North Korea's advancing weapons program.

Key points: A US Navy statement says the aircaft carrier USS Carl Vinson left Singapore on Saturday

A US Navy statement says the aircaft carrier USS Carl Vinson left Singapore on Saturday President Donald Trump and his South Korean counterpart agree to stay in close contact about North Korea and other issues

President Donald Trump and his South Korean counterpart agree to stay in close contact about North Korea and other issues The move follows North Korea's recent ballistic missile tests and continued pursuit of a nuclear program

The US Pacific Command directed the carrier group to sail north to the western Pacific after departing Singapore on Saturday, a US Navy statement said.

Commander of the US Pacific Fleet, Admiral Harry Harris, said the deployment followed recent provocations by Pyongyang.

The carrier group includes the aircraft carrier USS Carl Vinson, with support from several missile destroyers and missile cruisers.

The vessels will operate in the western Pacific rather than making previously planned port visits to Australia.

Earlier this week, North Korea launched a ballistic missile into the East Sea just ahead of a meeting between US President Donald Trump and Chinese President Xi Jinping.

During their talks in Florida, Mr Trump pressed his counterpart to do more to curb North Korea's nuclear program.

Mr Trump has said he would be ready to act unilaterally to address North Korea's nuclear program if China does not step up to help with the matter.

The naval deployment comes days after a US missile strike on an air base in Syria, which the Pentagon said was involved in a chemical weapons attack.

US Navy guided-missile destroyer USS Porter conducted the strike operations while in the Mediterranean Sea. ( AP: Ford Williams/US Navy )

North Korea denounced the strike as an "unforgivable act of aggression" and one that proved its nuclear weapons were justified to protect the country against Washington's "evermore reckless moves for a war".

The White House said Mr Trump and South Korea's Acting President Hwang Kyo-ahn spoke on Saturday by phone and agreed to stay in close contact about North Korea and other issues.

The strike group has participated in exercises with the Japan Maritime Self Defence Force and Republic of Korea Navy, various maritime security initiatives, and routine patrol operations in the South China Sea.

North Korean officials, including leader Kim Jong-un, have repeatedly indicated an intercontinental ballistic missile test or something similar could be coming, possibly as soon as mid-April.

Wires/ABC