TOKYO The United States and Japan vowed on Thursday to deepen military cooperation in the face of North Korean "belligerence".
U.S. Defense Secretary Robert Gates, on an Asia trip that started in China and will end in South Korea on Friday, said all major regional powers hoped to ease tensions on the Korean peninsula.
"If there is a common theme in my visits, it is the common interest of the United States, Japan, the Republic of Korea and China for there to be stability and peace on the Korean peninsula," Gates said.
Gates earlier this week warned that Pyongyang was becoming a direct threat to the United States and could develop inter-continental ballistic missiles within five years.
He also suggested that the sinking of a South Korean warship and the shelling of a South Korean island last year was raising pressure on South Korea to shift from a policy of restraint toward one of military response, were Pyongyang to strike again.
"The key on the Korean peninsula, as I discussed in China and discussed in Japan, is to prevent another provocation from happening," he said.
The North has appealed almost daily for talks since the start of the year, but Gates called on Pyongyang to make concrete gestures that it was serious about negotiations.
Gates and his Japanese counterpart, Toshimi Kitazawa also agreed to strengthen defense cooperation, and discussed the potential export to allies of missile defense capabilities both countries are jointly developing. Pentagon officials hope Japan will buy U.S. fighter jets, when upgrading its fleet of aging F-4 Phantom fighters.
U.S. relations with Tokyo frayed after the Democratic Party of Japan swept to power last year vowing to forge more equal ties with the United States and review an agreement on relocating a U.S. Marine airbase on Japan's Okinawa island.
But wariness over a rising China and an unpredictable North Korea has bolstered incentives to strengthen the alliance.
Gates said he spoke with Japanese leaders about "the challenges associated with China's growing military strength."
His comments came just two days after the first test flight of a Chinese stealth fighter jet. U.S. officials are also concerned about China's faster-than-expected advances in its anti-ship ballistic missile program, which could challenge U.S. aircraft carriers in the Pacific.
Kitazawa said both Japan and the United States agreed it was important for the international community to "keep working on China, so that it will take cooperative actions as a responsible major power in the international society."
Relations between Japan and China soured last year after a flare-up of a territorial dispute involving islands known as the Senkaku in Japan and Diaoyu in China.
(Editing by Miral Fahmy)