U.S. Secretary of State John Kerry says the United States and its allies in east Asia are "united" against threats from North Korea.
Kerry was speaking at a Tokyo university on April 15, on the last stop of his Asian tour.
"One thing is certain: We are united. There can be no confusion on this point," Kerry said. "The North's dangerous missile program threatens not only North Korea's neighbors but it threatens its own people."
Kerry called on Pyongyang to show it is complying with past international commitments on denuclearization.
"The burden is on Pyongyang," Kerry said. "North Korea must take meaningful steps to show that it will honor commitments that it has already made and it has to observe laws and the norms of international behavior."
At the same time, Kerry urged further talks and engagement with the North in the quest for regional peace.
"I am optimistic that we can agree on tangible steps to enhance stability and security in the region," Kerry said. "All of our partners, all of them, have a role to play in supporting regional peace and prosperity. And that includes ultimately trying to make a partner out of North Korea, and make it part of this vision."
'State Of War'
Also on April 15, a spokesman for South Korea's Unification Ministry said it was "regrettable" that the North has rejected recent offers of dialogue aimed at reducing tensions on the Korean Peninsula, which have been elevated since the North conducted its third nuclear-weapons test in February.
Pyongyang said on April 14 that the offers were "empty" and "a clever trick."
North Korea has issued a series of threats in recent weeks, saying its missiles and artillery were targeting U.S. bases and that a “state of war” exists with South Korea.
NATO Secretary-General Anders Fogh Rasmussen was also in Tokyo on April 15. He told Reuters television that one of the greatest risks regarding North Korea "is the unpredictability."
"We consider these provocative actions -- missile launches, nuclear tests -- a threat to regional and international peace, security, and stability, and we urge the North Korean leadership to stop these provocative actions, to comply with the United Nation's security council resolutions," Rasmussen said. "At the same time, we commend all efforts to pursue dialogue and find peaceful solutions to this conflict."
The comments by Kerry and Rasmussen in Japan come as North Korea observes a holiday marking the 101st birthday of the state's late founder, Kim Il Sung.
Analysts have speculated Pyongyang might use the occasion to test a medium-range ballistic missile, but North Koreans appeared to ignore the tense situation in the region as the three-day holiday got under way on April 15.
Children skipped through Pyongyang streets carrying flags and banners, while parents of newborns paraded with baby carriages. A mass pilgrimage was held to the Kumsusan Palace, where the tombs of Kim and his son, former North Korean leader Kim Jong Il, are located.
Based on reporting by AP, Reuters, and AFP