As this article in the Japan Times shows (link in English), senior cabinet and party officials have been cool to the news out of Beijing. The Japanese government, of course, was not in position to insist on the importance of conditions, and must accept Pyongyang's about-face. But Japan doesn't have to like it:
"We really don't know why the North has decided to return to the talks," a senior Foreign Ministry said on condition of anonymity.
"(North Korea) has just returned to the talks after walking out on them. We are trying not to attach too much value on the return itself," the official said, stressing that Japan's goal is the total end of Pyongyang's nuclear threat, not just the resumption of the talks.
Tokyo has also refrained from issuing a formal statement on Pyongyang's return to the talks, the official said.
As this New York Times article shows, the response in the US government and the Washington policymaking community is split between those who believe that some positive outcome could result from the talks and those who believe that North Korea is just stalling for time. One major fault line appears to be between -- surprise! -- the State Department on the one hand, and Rumsfeld-Cheney duo on the other (supported by experts at AEI and the Heritage Foundation).
Now, as for me, I fall somewhere between the two. I do not expect these talks to disarm North Korea, as I've said on a number of previous occasions. At the same time, I don't think the US loses much by participating in the talks. The US should not, of course, be in a hurry to make major concessions; North Korea's bargaining history means that it must make the first substantial step or any "agreement" reached would lack all credibilty.
In any case, North Korea isn't the only country buying time through negotiations -- an argument made by AEI's Nicholas Eberstadt in the Times article. The talks give the UN time to figure out what exactly is included in the sanctions, and it gives the US time to coordinate with its allies and map out a game plan for how to contain a nuclear North Korea over the long term, which at the moment could be a very long time.