Japan will "be destined to pay a heavy price" if it dares to cross the red line of the Taiwan question, a Chinese defense spokesman said on Thursday.

Jiang Bin, a spokesman for the Ministry of National Defense, made the remarks at a regular news conference in Beijing in response to Japan's claim that a plan to station medium-range surface-to-air missiles on Yonaguni Island, about 110 kilometers east of Taiwan, was making steady progress.

In addition, Japanese Defense Minister Shinjiro Koizumi said on Sunday that the deployment will "lower the chance of an armed attack", while claiming it would not heighten regional tensions, Bloomberg reported.

At the briefing, Jiang stressed that the Taiwan question is purely China's internal affair.

"How to solve the Taiwan question is a matter for the Chinese, and has nothing to do with Japan," he said.

This year marks the 80th anniversary of Taiwan's restoration to China, Jiang added.

"Instead of repenting its war crimes of invading and colonizing Taiwan, Japan is taking an extremely wrong approach by suggesting military intervention in a so-called Taiwan contingency," he said.

This dangerous approach will uproot the post-World War II international order and lead Japan to repeat the mistakes of its militarist past, he emphasized.

"The People's Liberation Army has strong capabilities and reliable means to defeat any aggressors," Jiang said, warning that should Japan dare to cross the red line and invite trouble upon itself, it is destined to pay a heavy price.

Jiang also criticized Japan's recent actions in the military and security fields, urging the country to fully repent its war crimes and immediately abandon attempts at constitutional revision and military expansion.

"Any attempt to repeat the evil path of aggression and expansion and undermine the post-World War II international order will not succeed," he said.

According to Kyodo News, Japan recently exported domestically produced Patriot surface-to-air missile interceptors to the United States. It was believed to be the first export of lethal weapons since Japan relaxed controls on its arms shipments.

Separately, The Asahi Shimbun reported that Japan's ruling Liberal Democratic Party has begun discussions on revising the National Security Strategy and two other defense documents. The review could cover the Three Non-Nuclear Principles — not possessing, not producing and not permitting the introduction of nuclear weapons — as well as a further increase in defense spending.

The spokesman said it remains an "ironclad fact" that Japan was a defeated country in World War II, noting that international treaties and instruments, including the Cairo Declaration, the Potsdam Proclamation and the Japanese Instrument of Surrender, clearly banned Japan from rearmament.

"The international community must be on high alert against Japan's revisioni