Another large Chinese Coast Guard vessel was spotted last month in the South China Sea, close to the Philippines. Authorities in Japan and other countries are closely monitoring the ship dubbed "The Monster."

Some Philippine newspapers report that the vessel is "China Coast Guard 5901." It's the same size as the one that is often seen in the East China Sea.

In May, "China Coast Guard 5901" reportedly entered the Philippines' exclusive economic zone and navigated waters near Scarborough Shoal, which is effectively controlled by China.

China is ramping up pressure by firing water cannons at Philippine vessels in the South China Sea. It is using so-called "grey zone tactics" that fall short of armed conflict to increase pressure on nearby countries.

Participants at the Asia security conference held in Singapore spoke about the situation.

Admiral Ronnie Gil Gavan, Philippine Coast Guard Commandant, said fire monitors are not meant to light up fire, but to save lives and properties from fire.

Seguchi Yoshio, Vice Commandant of the Japan Coast Guard, said Coast Guard ships must not be used as tools to change the status quo.

Lieutenant General Jing Jianfeng, the deputy chief of China's Central Military Commission's Joint Staff Department, responded sharply, saying that violations of rights and provocations cannot be tolerated. He added that China is determined to protect its sovereignty, maritime rights and interests.

The Philippine Coast Guard has a shortage of patrol boats. Two patrol ships have been provided by the Japanese government. With a length of 97 meters, they are among the largest of the Philippine Coast Guard vessels.