The four Chinese vessels first entered Kinmen's waters from Fuxingyu, Zhaishan, Liaoluo and the southern entrance of Beiding at 8:50 a.m., the CGA was quoted as saying by Focus Taiwan.

the CGA dispatched four patrol vessels, responding one-on-one to the Chinese boats, and broadcast warnings ordering them to leave in Mandarin and English, it added.

The Chinese vessels left at around 11 a.m., but re-entered Kinmen's restricted waters at 2:45 p.m., upon which four patrol vessels were dispatched to observe the intruding vessels again, the CGA said

At 5 p.m., the CGA vessels together monitored the Chinese vessels leave the restricted waters, it added.

CGA claims that China's Coast Guard has frequently entered Taiwan-controlled waters near the Kinmen Islands.

What is the basis of China’s claim over Taiwan?

The basis of China’s claim over Taiwan dates back to 1945 when Japan lost its control over the island in 1945,post-World War Two. The 1949 Chinese civil war lead to communists taking control and Chiang Kai-shek the one who lost fled to Taiwan. He ruled it for many decades. This is where China’s claim to Taiwan emanates. The very fact that Chiang Kai-shek came to Taiwan and was not indigenous to the place is Taiwan’s argument against the claim.

The question is why is Taiwan important to China?

“A lot of things actually, which of course are related to Taiwan but not necessarily direct to Taiwan. It's more about (China's) relationship changing with United States – or we should say Western Countries, mainly United States and China. Taiwan then happens to become key player and main actor in this dynamics,” said Alice.

100 miles from the coast of China, Taiwan is an island, that is located in the “first island chain,” this positioning makes it crucial to the US foreign policy.

US-Sino relations hinge on, ‘One China Policy,’ it acknowledges that, “there is only one Chinese Government." The US recognises its formal ties with China. With Taiwan the US shares independent strong “unofficial” relations.