By Chris Hogg
BBC News, Tokyo
Japan's PM Shinzo Abe says his country cannot tolerate a nuclear-armed North Korea and wants closer international co-operation to stop such an outcome.
In a BBC interview, Mr Abe also defended his plans for Japan to develop a more assertive foreign policy.
He made clear he believes North Korea poses a very grave threat to the world.
Mr Abe begins a trip to Europe in London where he is due to hold discussions with the British Prime Minister Tony Blair.
"If the North Koreans are to possess nuclear weapons that may lead to the proliferation of weapons of mass destruction," he said.
"That could fundamentally undermine the non-proliferation regime, which may then lead to more problems regarding Iran for example."
Mr Abe's visit to Europe is an opportunity for a prime minister who is just a few months into the job to start to build closer relationships with Western leaders.
It comes as he presses ahead at home with plans to re-write the country's pacifist constitution, a move that is causing some concern.
Mr Abe sought to reassure his critics, pointing out that Japan had upheld freedom and democracy for six decades, and saying he plans to discuss with Nato officials what the country can do to promote global peace and stability.
Significantly, Mr Abe used the interview - at his offices near the National Diet building in Tokyo - to raise the issue of the abduction of foreign nationals by North Korea.
It was his campaigning on this issue that helped to bring him to prominence in Japanese politics and he takes every opportunity he can to press the point.
Snatched in the '70s and '80s
Used as cultural trainers for N Korean spies
Five allowed home in 2002
Five children now freed from N Korea
Eight said to be dead, others missing
"We believe that this abduction issue is a grave infringement of basic human rights," he said, insisting that "all countries around the world need to address it".
He also said that according to testimonies provided by abductees, who were kidnapped by the North in the 1970's and 80's to train its spies, there are some Europeans.
This has not been verified. North Korea returned five Japanese nationals in 2002 but claimed that others who had been abducted had died.
After visiting London, Mr Abe will also make stops in Berlin, Paris and Brussels.
There he will hold discussions with Nato leaders about closer co-operation between Japan and the alliance.
"By deepening the partnership between Japan and Nato member countries we shall be able to address various problems, conflicts and also peace-building," the prime minister said.
Japan is already working with Nato, supporting operations in Afghanistan for example.
But Mr Abe insists that other nations have nothing to fear from a more assertive Japan.
"I believe we will be able to gain the understanding as well as the confidence of the world regarding Japan's assertiveness" he said.