In the three security and defense documents Japan adopted on Friday, China was described as "an unprecedented strategic challenge", which marks a milestone shift from nine years ago when China was depicted as a strategic partner in the first national security strategy Japan released in 2013.

What does the shift mean and what is behind it? China has done nothing to warrant such a reaction from Japan. China's leaders have reiterated time and again that it only seeks a peaceful rise, as verified by what it has been doing: the Belt and Road Initiative and various kinds of partnerships it has sought for economic cooperation with other countries. It has been Japan's largest export market and its largest trading partner for years.

It is natural for the two countries to have differences on a wide range of issues. It is also natural for China, the world's second-largest economy with the world's largest population, to have a defense capability that is compatible with its status as a major country and fit for the times.

It was Japan which invaded many countries during World War II, and it was invading Japanese forces that committed horrible atrocities in China and other countries. If there is any potential threat to peace in East Asia, it should be the revival of the militarist mentality in the minds of Japanese politicians.

Describing China as "an unprecedented threat" is only a pretext Japan's Cabinet is using to expand its military. That explains why Japanese Prime Minister Fumio Kishida early this month set a new target for military spending over the next five years of 43 trillion yen ($318 billion), an almost 60 percent increase over the figure of 27 trillion yen between 2019-23.

It is not so much China posing a threat to Japan as some Japanese politicians in power having the ambition to develop Japan into a strong military power.

By fast expanding its military capability, Japan is embarking on a road that is contrary to its so-called pacifist Constitution, which Japan's right wing politicians have tried to revise. The expansion of its military might is the de facto revision of the Constitution, which warrants vigilance of its neighbors in East Asia against the rise of Japanese militarism.

When it comes to China-Japan ties, labeling China as "an unprecedented challenge" is against the spirit of the four political documents signed between the two countries, and undermines political trust between the two nations as well.

Given its history of invasion of a number of countries in East Asia, Japan's expansion of its military capability undoubtedly poses a potential threat to peace in the region, and its neighbors have enough reason to be suspicious of the motivation behind its expansionist new security strategy.