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

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

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.

Jiang reiterated 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.

He also noted that this year marks the 80th anniversary of Taiwan's restoration. Instead of repenting for its war crimes of invading and colonizing Taiwan, Japan is "taking an extremely wrong approach by suggesting military intervention into a so-called Taiwan contingency," he said.

Jiang said Japan's actions risk uprooting the post-World War II international order and repeating the mistakes of its militarist past.

"The PLA has strong capabilities and reliable means to defeat any aggressors," he said, warning that if Japan dares to cross the red line and invites trouble for itself, it will be "destined to pay a heavy price."