The Japanese Foreign Ministry has sent out an e-mail to all its diplomats overseas instructing them to avoid using Korean Air for a month. It apparently took the step to protest against Korean Air's inaugural flight of its new A380 jumbo jet over the Dokdo islets on June 16, claiming the aircraft invaded Japanese airspace. Tokyo had already lodged a protest via its embassy in Korea, and Japan's Foreign Minister Takeaki Matsumoto held a press conference to complain.

Territorial matters are for governments to handle. It is beyond comprehension and unprecedented for a government to take retaliatory measures against a private business in another country without going through the host government. Even Japan's Asahi Shimbun newspaper wrote, "It is rare for the government to reject a specific civilian carrier."

Japanese political sentiment is heading in a strange direction. Tokyo seems to have lost its way, especially over territorial disputes. The trend has become even more apparent after it failed to respond effectively to Chinese moves to assert ownership of the Diaoyutai or Senkaku Islands, over which Japan has administrative control, and a visit by Russian President Dmitry Medvedev to the Kuril Islands, which Japan claims, to emphasize Moscow's control over them. The administration of Prime Minister Naoto Kan, which has its back to the wall after the Fukushima nuclear disaster, is losing its grip on domestic politics and is playing to popular sentiment. But it is only making matters worse.

The Korean Air boycott was apparently decided after opposition Liberal Democratic Party lawmakers lambasted the Foreign Ministry for not taking stronger retaliatory measures over the A380 flight over Dokdo.

It looks as if Tokyo is trying to placate the Japanese public by taking its frustration with China and Russia out on Korea. In March, Japan also caused an uproar here when its foreign minister, asked by a lawmaker who used to serve in the Self-Defense Force, answered that any attack by North Korea against Dokdo would be construed as an attack on Japanese territory.

The more unreasonably and absurdly Japan acts, the more difficult it will find it to gain the respect of its regional neighbors. And if relations with South Korea get worse, Japan will become isolated in Northeast Asia. It should be aware of the risk.