As many as 50 Taiwanese fishing boats entered territorial waters that Japan claims around the Senkaku Islands on Tuesday, a further escalation of the territorial dispute on the day that China put its first aircraft carrier into service.
Japan Coast Guard patrol vessels fired water cannons at the Taiwanese ships after the vessels refused to heed warnings not to enter Japanese waters in the morning. Eight surveillance ships dispatched by Taipei to accompany the fishing boats retaliated with water cannons against the Japanese ships.
When ordered to leave Japanese waters, the captain of one of the Taiwanese patrol vessels replied that the ships were operating in Taiwan's waters and engaged in legitimate activities. He also demanded that the Japanese Coast Guard withdraw.
Many of the Taiwanese ships were flying banners demanding that Japan hand over the territory to Taiwan, which knows the chain as the Tiaoyutai. Further clouding the issue, China lays claims to the isolated islands and calls them the Diaoyu.
Coast Guard officials in Okinawa, which administers the islands, said there were no reports of any injuries in the clashes.
All the vessels had left Japanese territorial waters before midday, although monitoring aircraft have since identified a further six Chinese patrol ships sailing just outside the area around the islands.
China's top military leaders attended the commissioning ceremony for the aircraft carrier, the Liaoning, at a naval base in Dalian, according to the Chinese Defence Ministry.
The ministry added that the vessel will help "effectively safeguard national sovereignty, security and development interests."
The 67,000-ton carrier – started by the Soviet Union before the incomplete hulk was sold to China in 1998 – is capable of carrying as many as 30 fixed-wing aircraft and helicopters.
While it may be relatively rudimentary in aircraft carrier technology, the commissioning of the Liaoning makes China the only nation in East Asia with the capability to project its naval and air power and sends a clear message to its neighbours.
In yet another territorial dispute involving Japan, South Korea refused permission for a Japanese warship taking part in a joint naval exercise with Korea, Australia and the US to dock at one of its ports.
Tokyo has lodged an official protest with Seoul and a Japanese diplomat quoted by the Sankei newspaper in Tokyo described the decision as "extremely rude."
South Korea and Japan are disputing the sovereignty of two small islands that lay halfway between the two nations and are known as Dok-do in South Korea, which has stationed a unit of armed police on the islets.
Please follow Military & Defense on Twitter and Facebook.