China is on high alert over the true intentions behind Japan's military moves, said Chinese Foreign Ministry spokesperson Hua Chunying on Thursday.

Hua made the remarks after the Japanese newly-commissioned helicopter-based escort ship Kaga went into service on Wednesday.

"The situation in the South China Sea is stable through the joint efforts of China and ASEAN countries. China and its neighbors will never allow Japan to make trouble," said Foreign Ministry spokesperson Hua Chunying.

In recent years, Japan has sensationalized the so-called "China threat," as an excuse for expanding its military, Hua said at a routine press briefing.

For historical reasons, the international community, especially Japan's neighboring countries, keep a close eye on Japan's military moves, according to Hua.

"We have every reason to remain on high alert," she added.

The original Kaga was sunk by the US military during World War Two. Japan should learn the lessons of history, Hua said.

"We hope the Kaga's reappearance is not a resurgence of Japanese militarism," she said.