Have the Chinese warships off Australia’s coast broken any laws?

UNSW Canberra’s maritime security expert, Douglas Guilfoyle, explores where international law and military behaviour overlap.

On Thursday 20 February it was announced that three Chinese warships had been operating in Australia’s 200-nautical-mile Exclusive Economic Zone (EEZ) off the east coast, for a week, opens in a new window.

On the following Friday and Saturday, opens in a new window, on the high seas outside the Australian EEZ, the vessels conducted unannounced live-fire exercises in the Tasman Sea some 340 nautical miles from Sydney.

Australia learned of the exercises from warnings given by the warships, opens in a new window to aircraft in the region and criticised the lack of notice. Australia would normally give 12-24 hours’ notice of such exercises. New Zealand, opens in a new window would have preferred 24-48 hours’ notice.

Yet both countries have accepted that these activities did not breach international law. Similarly, Australia did not protest the missions of Chinese ‘spy ships’ off our coasts in 2023, opens in a new window and 2024, opens in a new window.

What has China said about such activities in the past?

Notably, China generally takes a very dim view of other countries conducting military activities in its 200-nautical-mile EEZ.

In 2001, a US surveillance plane collided with one of two Chinese F-8 fighter jets sent to shadow it, some 90 nautical miles off the coast of China’s Hainan Island.

The collision resulted in the death of a Chinese pilot and the brief detention of the US aircrew after an emergency landing on Hainan. A Chinese foreign ministry spokesperson, opens in a new window said “the US plane's actions posed a serious threat to the national security of China” and violated the principle that in (or over) the EEZ military activities “should respect the rights of the country concerned”.

Similarly, senior Chinese military officials, opens in a new window have expressed the view that “military activity that is harmful to the coastal state’s sovereignty or security in the exclusive economic zone is illegal”.

China has also dropped flares, opens in a new window in the path of Royal Australian Air Force helicopters and fighters in the South China Sea in incidents in 2024 and 2025, saying Australia was “violating Chinese sovereignty and endangering Chinese national security”.

Oddly enough, China did not seem concerned enough by Australian ‘national security’ to refrain from its own ‘spy ship’ transits off Australia in 2023, when it observed US-Australian training operation Talisman Sabre, or in 2024 when one of its intelligence vessels passed “within 50 nautical miles of a sensitive defence facility”, opens in a new window on the west coast.

What does international law say?

The UN Convention on the Law of the Sea (UNCLOS) does establish the right of coastal States to “sovereign right and jurisdiction” over the living and non-living resources of a 200-nautical-mile EEZ off their coasts.

Contrary to previous Chinese pronouncements (like those detailed above), this is not a zone in which there is any express right to protect national security or prohibit foreign military exercises.

And, in fairness, China’s own EEZ law, opens in a new window asserts no such rights. However, China has consistently pointed to language in UNCLOS stating that foreign states operating in the EEZ should operate with “due regard for the rights, opens in a new window” of the coastal State.

This position may explain why Chinese vessels left the Australian EEZ to conduct their live fire exercises on the high seas. If it had not, a “turn about is fair play” argument could be made for live fire exercises to be conducted within 200 nautical miles of the Chinese mainland by other countries.