Kawagoe: US President Donald Trump ramped up his tough rhetoric against North Korea when he arrived in Japan on Sunday, saying that the United States and its allies are prepared to defend freedom and that "no dictator" should underestimate America's resolve.

Trump kicked off a 12-day Asian trip and is looking to present a united front with Japan against North Korea through meetings with Prime Minister Shinzo Abe amid heightened tensions over Pyongyang's nuclear and missile tests.

He told reporters on Air Force One en route to Asia that North Korea would figure prominently in discussions during the trip. He also singled out trade, which he said had been "badly handled" in the region for years.

Trump has rattled some allies with his vow to "totally destroy" North Korea if it threatens the United States and his dismissal of North Korean leader Kim Jong Un as a "rocket man" on a suicide mission.