The Japanese foreign minister says Japan and the United States cannot allow North Korea to have nuclear weapons.
Fumio Kishida was speaking at a news conference in Tokyo on April 14 after talks with U.S. Secretary of State John Kerry.
Kerry said the United States was "fully committed" to protecting Japan.
Kerry is in Japan on the last stop of an Asian tour aimed at bolstering support for curbing North Korea's nuclear program.
"The goal of both China and the Republic of Korea is the denuclearization of North Korea and that was strongly -- strongly -- reaffirmed by my counterparts in Beijing yesterday," Kerry said.
"We are committed to take action together. We -- Japan, the United States, and the other countries that I have met with in the last two days -- are committed to make that goal of denuclearization a reality."
In Beijing on April 13, Kerry and senior Chinese officials agreed that diplomacy was the best way to "denuclearize" the Korean Peninsula.
Chinese officials did not say, however, whether Beijing will pressure ally Pyongyang, something Kerry is eager to see China do.
China's Xinhua news agency said in a commentary that Washington had itself been "fanning the flames" on the Korean Peninsula, a probable reference to recent U.S. military drills in South Korea.
North Korea has for weeks been threatening to attack the United States, South Korea, and Japan after the United Nations tightened sanctions on the isolated state in response to its third nuclear weapons test in February.
Japan has deployed U.S.-made Patriot antimissile batteries around Tokyo amid mounting concern North Korea may be preparing to launch one of its medium-range missiles.
Based on reporting by Reuters, AFP, and AP