While visiting Japan on Monday, President Donald Trump touted "great respect" between the US and North Korea.

Trump said he viewed North Korea's recent missile tests "differently" from his national security adviser, John Bolton.

The president also disagreed with Japanese Prime Minister Shinzo Abe on the tests, which may have violated UN Security Council resolutions.

President Donald Trump has disagreed with other world leaders and his own staff on whether North Korean missile tests violated UN Security Council resolutions.

Trump on Friday said he was "not bothered" by North Korea's missile tests earlier this month, though top Trump officials, including the national security adviser, John Bolton, have said the tests violated UN Security Council resolutions.

"My people think it could have been a violation, as you know," Trump told reporters on Monday at a joint news conference with Japanese Prime Minister Shinzo Abe, noting that no nuclear or long-range missiles had been tested. "I view it differently."

Abe said he disagreed with Trump's view on North Korea's missile testing but added that he agreed with Trump on efforts to denuclearize the Korean Peninsula.

"I personally think that lots of good things will happen with North Korea," he said, adding that there was "good respect" built between the US and North Korea.

Trump is in Japan for a four-day trip. His discussions with Abe were said to have included the decades-long issue of North Korea's abduction of about a dozen Japanese nationals in the 1970s and 1980s, with Trump promising to work with Abe to bring the remaining abductees home.

The president was also asked about his tweet over the weekend that played off North Korean leader Kim Jong Un's recent mocking of former Vice President Joe Biden, who is now a leading candidate for the 2020 Democratic presidential nomination.

"North Korea fired off some small weapons, which disturbed some of my people, and others, but not me," Trump tweeted. "I have confidence that Chairman Kim will keep his promise to me, & also smiled when he called Swampman Joe Bidan a low IQ individual, & worse. Perhaps that's sending me a signal?" (Trump re-sent the tweet with Biden's name spelled correctly.)

Bolton on Saturday said the Trump administration had "not heard much" from North Korea since the summit in Hanoi, Vietnam, in February, during which Trump refused Kim's request to lift economic sanctions in exchange for dismantling only part of its nuclear weapons system, as reported by The New York Times.