During their meeting last week, the South Korean and Japanese defense chiefs agreed that Tokyo would get Seoul’s consent before exercising its right to collective self-defense in an emergency on the Korean Peninsula.

Japanese Defense Minister Gen Nakatani reassured his South Korean counterpart Han Min-koo that Japan would never send troops to the peninsula without prior consent from South Korea. He was quoted by a South Korean defense official as saying that “our self-defense force will launch military actions in other countries’ territory only after getting consent from the countries concerned in any circumstances, in accordance with international law.”

But he avoided giving a clear answer to Han’s request that Tokyo get Seoul’s consent in case of an attack on North Korea’s missile bases. Appearing on Japanese television earlier last month, Nakatani said Japan’s military may strike North Korean missile bases if U.S. forces come under attack.

His remark came shortly after Washington and Tokyo revised the guidelines for their defense cooperation to allow Japan to fight alongside the U.S. and other allies even when it is not under assault from a hostile country by exercising the right to collective self-defense.

Though the U.S.-Japan pact stipulates that their joint military operations will be “in accordance with international law, including full respect for sovereignty,” some critics here have noted that the expression is “too vague.” They are also skeptical about whether Tokyo will be willing to seek Seoul’s consent before it responds to an emergency on the peninsula.

Seoul has called on Washington and Tokyo to better reflect its views in drawing up operational plans based on the revised guidelines.

The stance taken by the Japanese defense chief implies that Tokyo will limit the area where its military operations need Seoul’s consent to South Korean territory, not the whole peninsula. This is difficult for South Korea to accept, as the Constitution regards North Korea as part of its territory.

Apart from the legal aspect, it is reasonable for Seoul to be concerned that Japanese military action against the North may prompt the belligerent regime to attack the South. Excessive involvement by Japan may also prod China to intervene in an emergency on the peninsula.

Koreans still have a vivid memory of a military conflict between Japan and China for hegemony over the peninsula in the late 19th century. Japan’s victory opened the way for its colonial rule of Korea from 1910-45.

Seoul has recently felt an increasing need to strengthen security cooperation with Tokyo to cope with the volatile situation in the North. But it certainly is a prerequisite for closer military cooperation between South Korea and Japan that the former’s sovereignty is not affected.

Seoul needs to get Tokyo and Washington to consent to this principle in their coming consultations on the scope and conditions of Japan’s use of the right to collective self-defense.