US carrier USS Carl Vinson in exercises with Japan

U.S. Navy aircraft carrier, the USS Carl Vinson. Photo / AP

An American aircraft carrier heading towards the Korean Peninsula began joint exercises last night with Japanese naval ships in the Philippine Sea.

Two Japanese destroyers joined the USS Carl Vinson and two other US warships as they continued their journey north in the western Pacific Ocean, the US Navy said.

The Vinson had cancelled a scheduled visit to Australia to divert toward North Korea in a show of force, though it still conducted a curtailed training exercise with Australia before doing so. Tensions are elevated on the Korean Peninsula, with the Trump Administration saying that all options are on the table, and indications that North Korea may be preparing to test a nuclear weapon or long-range missile.

Two Japan Maritime Self-Defence Force destroyers left Sasebo port in southern Japan to join the Vinson strike group. The US group also includes a guided-missile cruiser and a guided-missile destroyer.

The Navy called the exercise "routine".

Australian Foreign Minister Julie Bishop has hit back at North Korea over its threat of a nuclear strike on Australia saying Pyongyang should be investing in the welfare of its "long-suffering citizens" rather than weapons of mass destruction.

The rogue state turned its sights on Australia on Saturday, threatening nuclear retaliation after Bishop said North Korea could be subject to further Australian sanctions.

"If Australia persists in following the US moves to isolate and stifle the DPRK and remains a shock brigade of the US master, this will be a suicidal act of coming within the range of the nuclear strike of the strategic force of the DPRK," Pyongpang said.

Undeterred, Bishop said yesterday that North Korea's threats of nuclear strikes against other nations further underlines the need for the regime to abandon its illegal nuclear weapons and ballistic missile programmes.

North Korea's state-run KCNA news agency had quoted a Foreign Ministry spokesman accusing Bishop of "spouting a string of rubbish against the DPRK over its entirely just steps for self-defence" and Australia of "blindly and zealously toeing the US line".

- AP, AAP