North Korea has denounced the US deployment of a naval strike group to the region, warning it is ready for "war" as Washington tightens the screws on the nuclear-armed state.

The strike group, which includes the Nimitz-class aircraft supercarrier USS Carl Vinson, cancelled a planned trip to Australia this weekend to head to the Korean peninsula in a show of force.

"This goes to prove that the US reckless moves for invading the DPRK have reached a serious phase," a spokesman for North Korea's foreign ministry said. "The DPRK is ready to react to any mode of war desired by the US."

President Donald Trump, fresh from ordering a missile strike on Syria, which was widely interpreted as a warning to North Korea, has asked his advisers for a range of options to rein in Pyongyang, said a US official.

Mr Trump has previously threatened unilateral action against Pyongyang if China - North Korea's sole major ally - fails to help curb its neighbour's nuclear weapons ambitions.