China's navy revealed for the first time that all three Chinese naval fleets - South Sea, East Sea and North Sea fleets - had conducted a joint large-scale exercise in September, amid the controversy over South Korea's deployment of the Terminal High Altitude Area Defense (THAAD) system.
The exercise involved more than 100 vessels and tens of warplanes in a combat drill using live ammunition in the Yellow Sea and Bohai Sea, according to an article posted on the Chinese Navy's official website on Monday.
The article also mentioned two other large-scale drills in the South and East China seas in July and August, which were earlier reported.
When asked why the navy kept the September secret until now, Li Jie, a Beijing-based military expert, told the Global Times that China was pressuring South Korea but avoided going too far to provoke Seoul, because the US ally at that time had not decided on the THAAD deployment.
Li said China was hoping South Korea would decide not to deploy THAAD.
Japan has set up a commission, headed by State Minister of Defense Kenji Wakamiya, to examine the potential benefits of placing THAAD systems on its territory to increase its defense capabilities against a potential North Korean ballistic missile threat, Reuters reported on Friday.
China Monday urged Japan to act prudently in the military and security fields and avoid unsettling regional stability, the Chinese foreign ministry told the Global Times on Monday.
"We were concerned about the news reports. China's position on the deployment of the THAAD is very clear and remains unchanged," Geng Shuang, a spokesperson for the foreign ministry said.
Japan's military and security activities are watched closely by its Asian neighbors and the international community because of its history, he said.
"We hope Japan [will] play a constructive role in boosting regional peace and stability, and not to the contrary," said the spokesperson.
He called the current Korean Peninsula situation "complicated and sensitive."