The "hermit state" as some Japanese diplomats call it has provided some information but not all that Japan, the United States and the other parties that make up the six party talks have demanded.
Pyongyang has failed to satisfy another key demand of the Japanese - that it explain what happened to Japanese citizens it abducted to train its spies.
That leads some in Japan to ask whether its government should stick with a process that seeks to bring North Korea back into the international arena.
But others fear the alternative would damage Japan's interests even more. Continuing its hardline stance could leave Tokyo increasingly isolated over the issue.
In the 1970s and 1980s, Japanese men and women, adults and children were kidnapped by the North Koreans and forced to teach their agents how to pass themselves off as Japanese.
No-one knows how many Japanese citizens the North Koreans abducted.
Relatives groups estimate the figure to be somewhere between 100 and 500.
North Korea has returned a handful but says the others are dead. The relatives of those who are missing do not believe them.
Trust issue
The abduction of its citizens is an emotive issue here in Japan.
It is not the only concern people have about North Korea. There are real fears about its nuclear weapon capabilities too. And the North has fired a ballistic missile over Japanese territory before.
But the abduction issue is more personal. It is easier for people to empathise with those who have lost loved ones, and as a result it is almost always referred to when politicians discuss how to handle the dispute between the two countries.
Ichita Yamamoto, an MP from Japan's governing Liberal Democratic Party, says it is a matter of real concern to his constituents.
"We are not sure how many people have been kidnapped," he says.
"We are not really sure if everybody is still alive. So the point is can the Japanese government trust North Korea or not?"
For Mr Yamamoto, the answer is no.
"We cannot trust them because they have betrayed us many times in our negotiation regarding this abduction issue".
U-turn claim
That lack of trust is a problem. The rest of the world, led by the United States, decided a year ago it would have to start to trust North Korea if it was to resolve the issue of what to do about Pyongyang's nuclear weapons.
Months and months of negotiations in the six party talks produced an agreement in which North Korea agreed to provide a full and complete declaration of its nuclear programmes and the US promised to start the process of removing North Korea from its list of states that it claims sponsor terrorism.
Prof Robert Dujarric, an American analyst from Temple University in Tokyo, says that pledge - what he calls "a traumatic shock" for the Japanese government - "humiliated" the administration in Tokyo.
Japan had believed that the United States was committed to a very hardline policy towards North Korea.
"This US 'U-turn', apparently with little or no prior consultation with Japan, made the Japanese look extremely stupid," the professor argues.
"Now they are totally isolated - the only country which advocates a continued hardline towards the North".
In the 12 months since that agreement was reached, Pyongyang has dragged its feet over its promise to reveal its nuclear secrets.
North Korea was supposed to produce the complete declaration of all of its nuclear programmes by the end of last year. It still has not, although US diplomats remain optimistic that it will.
If it does then it is likely that North Korea, a country which Japan still believes is still holding some of its citizens hostage, would be taken off the US list of terrorist states, a move that would dismay the Japanese.
Secret talks?
But Tomohiko Taniguchi, a spokesman for Japan's Foreign Ministry puts a brave face on it.
He insists that both Japan and the United States are in "complete understanding of what the other party is doing".
He points out that North Korea has not been de-listed from the list of terrorist-sponsoring nations yet. He insists the US would do nothing that would jeopardise their "indispensably important bilateral relationship".
Prof Dujarric sees it quite differently, arguing: "The United States does not care that much about Japan.
"It knows perfectly well that Japan has no option other than being an ally of the United States, so even if it is mistreated by the US what are the Japanese going to do?
"I think the US view of this is 'my way or the highway'."
What Japan could do, of course, is to try to engage North Korea itself.
To do this openly might not be possible - public opinion in Japan might not stomach it.
But perhaps it could be done in private. Indeed, perhaps negotiations are going on behind closed doors already.
There is a precedent. Hitoshi Tanaka is a former diplomat who held talks with the North Koreans in secret a few years ago on behalf of the prime minister at the time, Junichiro Koizumi.
Mr Tanaka points out that after a year of talks he produced an agreement in which North Korea first acknowledged the existence of the abductees.
The two sides agreed to deal with the question of nuclear weapons in a multi-lateral format, and to continue discussing the fate of the abductees as part of a process towards normalising the relationship between the two countries.
"I do not take the view that only pressure will resolve these questions," he says.
"There needs to be a very serious negotiation and if negotiations are not taking place today then I would be very disappointed, because without negotiation there is no resolution."
Officially at least, Japan does not talk to North Korea except within the forum of the Six Party Talks.
Tomohiko Taniguchi from the Foreign Ministry says he can not confirm whether or not secret negotiations are taking place.
Whatever the truth for now, as far as the Japanese political establishment is concerned the onus is on the government in Pyongyang to show willing, not the government in Tokyo.
And in the Japanese capital there is a remarkable degree of confidence that the United States will not let its own interests override those of its ally Japan.
