The People's Liberation Army's Eastern Theater Command said on Monday evening its forces are on high alert and will "engage the enemy on orders".

It published a very short article and a video on its WeChat account on Monday, the 95th anniversary of the founding of the PLA. In the article the command said its forces will "bury all invaders" and "march toward victory" in joint operations.

It did not elaborate on the intentions behind the brief words.

In the video clip attached to the article, a number of advanced weapons are shown in training or live-fire exercise operations, ranging from the DF-15B ballistic missile to PHL-03 multiple rocket launcher and J-20 stealth fighter jet.

A considerable proportion of the clip displays frontline units being mobilized to strike targets and ballistic missiles and tactical rockets flattening "enemies' structures".

According to information previously published by the Chinese military, the Eastern Theater Command has been the major actor in training, exercises and armed patrols in the Taiwan Straits and surrounding Taiwan.

Each time the United States has sent aircraft or warships to sail through the straits, it was always this command that dispatched forces to monitor and warn off US forces.

In another development, the maritime safety administration in Hainan province's Qinglan published a navigational notice on Monday evening stating military exercises are scheduled to take place in a certain area in the South China Sea from Tuesday to Saturday.

It released geographical coordinates of the drill zone, asking ships not participating in the event not to enter.