Japan's restrictions on exports of advanced chip-manufacturing equipment, which took effect on Sunday, are obviously in line with the United States' efforts to stymie China's ability to develop high-end semiconductors. With the revision of a Japanese trade ministry ordinance under the foreign exchange law, Japan added 23 chipmaking items to the list that requires approval for exports.

Against that backdrop, China certainly has more reasons to take Japanese Prime Minister Fumio Kishida's claim on Saturday that Sino-Japanese relations are "inseparable" with a pinch of salt.

That it took less than four months for such restrictions that will have far-reaching influences on the "inseparable" ties to be transformed from initiative to action, despite the concerns of the to-be-affected Japanese companies and the strong opposition of the Chinese side, exposes the Kishida government's determination to say one thing in relation to China and do another.

The Kishida government's duplicity is self-evident in its insistence that the move is based on Japan's national interests, does not target any particular country and is independent of any other country's will.

Its exclusion of a total of 42 "friendly" and "reliable" countries and regions from the restrictions — all US allies — further highlights the "coercive" nature of the practice as a geopolitical tool Japan is providing the United States.

Although it is not blocking the exports completely, it technically subjects both the Japanese companies and their Chinese partners to the whim of the Japanese government. That gives the latter a leverage to weaponize the technology and its trade for political purposes.

China will undoubtedly bear the brunt of the move, as it is the largest importer of these restricted Japanese export items, digesting about 30 percent of them.

By helping the US consolidate its China-excluded "chip alliance", Japan will not only lose its share of the Chinese semiconductor market but also harm the future of its own chip industry. The purpose of the US' chip alliance is to re-establish its semiconductor hegemony. If Japan blindly supports the US in that regard, its interests will also be damaged along with those of China.

Japan's chip-related exports to China are nearly double those of the US. While major US chip companies and the country's Semiconductor Industry Association are actively lobbying Washington not to block their deals with China, the collective silence of the Japanese companies and guilds explains how much work the Kishida government has been doing to muffle their opposition.

It remains to be seen how the Kishida government will help these Japanese companies find an alternative that can compensate them for the loss of a market that is as sizable and reliable as China's.