TOKYO, April 23 -- As U.S. President Barack Obama will be here soon for a state visit, Tokyo is eager to get his go-ahead signal to lift the country's ban on exercising collective self- defense right.

Washington needs to have a second thought before letting Japan go its own way though some U.S. politicians have thrown their weight behind Tokyo's move. Given the current regional situation and historical lessons, acquiescence to Japan's military ambition would be dangerous and may turn out contrary to what Washington has expected.

Under Japan's long-held "exclusively defense-oriented policy," defensive force is used only in the event of an attack against Japan, but in a scenario of collective self defense, the country could support another state militarily when the latter is under attack.

On April 16, Yosuke Isozaki, special adviser to Prime Minister Shinzo Abe said that Japan would seek to allow its Self-Defense Forces to respond to armed attacks on allies with "close ties" to Japan, leaving the definition of the term open to interpretations.

Former Director General of the Japanese Cabinet Legislation Bureau Osamu Akiyama said earlier that "lifting the ban on exercising the collective self-defense with restrictive conditions equals to allowing for the exercise of the right. There is no difference."

Under Article 9 peace clause of Japan's constitution, the state formally renounces war as a sovereign right and bans settlement of international disputes through the use of force. The pacifist constitution ensures peace and stability not only for Japan, but for the entire Asia-Pacific region as well. Tokyo's attempt to reinterpret self-defense right would render the clause meaningless and understandably arouse strong suspicion of Japan's neighboring countries and worsen the regional security environment.

Unfortunately, some senior U.S. officials have time and again connived at Tokyo's controversial act.

During his Japan tour earlier this month, U.S. Defense Secretary Chunk Hagel said that Washington "welcome Japan's efforts to play a more proactive role in the alliance, including by reexamining the interpretation of its constitution relating to the right of collective self-defense."

Former U.S. Director of National Intelligence and Commander of U.S. force in the Pacific Ocean Dennis Blair went even further by saying that "reinterpreting Japan's constitution will not result a more aggressive Japan and permitting Japan to exercise collective self-defense right doesn't mean Japan's militarism would reemerge. "

Such a sweeping statement is risky since Japan's move would change its postwar defense posture and disrupt the security landscape in the region, and trigger a chain reaction, a possible arms race to say the least.

Without a ban on collective self defense, a more "proactive" Japan could literally join the United States and South Korea in a preemptive strike against the DPRK, making the solution of nuclear issues on the Korean Peninsula even more difficult.

As Japan's close ally, the United States should tread carefully on the issue. Supporting Japan to lift the ban will endanger regional peace and stability, and harm U.S.strategic interest in the long run.