The United States is to deploy two additional ballistic missile defence destroyers to Japan to counter North Korean missile threats, the US defence secretary has announced during a visit to Tokyo.

Chuck Hagel said on Sunday that the threat posed by North Korea was a key focus of his talks with his Japanese counterpart, Itsunori Onodera.

"In response to Pyongyang's pattern of provocative and destabilising actions, including recent missile launches in violation of UN resolutions, I can announce today that the US is planning to forward-deploy two additional Aegis ballistic missile defence ships to Japan by  2017," Hagel said.

The US already has five of the Aegis warships in Japan, whose systems are designed to track and destroy incoming ballistic missiles.

Hagel added that the additional deployments would also provide more protection for the US mainland from such attacks.

The US announcement followed a move in October to deploy a second early warning American radar to Japan, stationed in Kyoto, and a decision to increase the number of ground-based missile interceptors in Alaska.

"These steps will greatly enhance our ability to defend both Japan and the US homeland from North Korean ballistic missile threats," Hagel said.

War of words

The announcement came as tensions with North Korea spiked again, with Pyongyang continuing to threaten additional missile and nuclear tests.

North and South Korea fired hundreds of artillery shells into each other's waters in late March in the most recent flare-up.

On Friday, North Korea accused the US of being "hell-bent on regime change''.

Pyongyang's deputy ambassador to the UN, Ri Tong-Il, also said his government "made it very clear we will carry out a new form of nuclear test'', but refused to provide details.

Source: Agencies