A Japanese expert on North Korea says Tokyo may have been unprepared for the speed with which Washington and Pyongyang narrowed their differences over the North's nuclear weapons. As a result, he says, despite a breakthrough in efforts to end Pyongyang's nuclear ambitions, Japan is staying its hard-line course in dealing with the North. Yuriko Nagano reports from Tokyo.

South Korea's chief negotiator Kim Kwan-se, right, shakes hands with his North Korean counterpart Maeng Kyong-il during their meeting at the North Korean border town of Kaesong, 15 Feb 2007

Despite this month's agreement in Beijing on shutting down North Korea's nuclear reactor, Pyongyang made no new pledges to resolve the issue of abducted Japanese citizens.

As a result, says Kokushikan University Professor Teruo Komaki, the Japanese government ended up taking a tough stance at the talks, and may have appeared to be isolated in the six-party talks.

At a recent briefing at Japan's Foreign Press Center, Komaki said there was a shift in U.S. attitude over recent months. He says this was in part because President Bush now faces tougher opposition in Congress. Komaki says Japan may not have been able to fully respond to the U.S. shift.

In December, it appeared that the United States and North Korea were far apart in talks aimed at ending Pyongyang's nuclear programs. Yet after meetings in January between U.S. and North Korean negotiators, and diplomatic maneuvering by Beijing, this month North Korea agreed to disable its main nuclear reactor. In return, South Korea, Russia, China and the United States will give North Korea 50,000 tons of oil.

Because of the abductee issue, Japan will not contribute oil, but it backs the agreement.

North Korea has admitted kidnapping 13 Japanese citizens in the 1970s and '80s to force them to train spies. Five were allowed to return home a few years ago, but Pyongyang says the others are dead. Tokyo says many more were snatched and wants a full accounting of all those missing.

Komaki says Japan has a key weapon in dealing with North Korea - its economy. He says Pyongyang realizes that if relations are normalized with Japan, the impoverished country will benefit. So, the professor says, Japan should stay the course on the abductee issue, and go back to dialogue and applying pressure.

Komaki rates the six-party talks as a positive step toward removing nuclear weapons from the Korean peninsula, but he is not completely optimistic about what lies ahead.

Komaki says his understanding is that with the conclusion of the latest round of agreements he expects to see a more difficult and hard round of negotiations to begin.

For starters, Komaki says it remains to be seen if North Korea will keep its pledge to shut down its reactor. He also notes that the agreement does not clearly mention Pyongyang's nuclear weapons.

North Korea, which tested a nuclear explosive last October, is thought to have at least one or more nuclear bombs and fuel for several more.