TOKYO — President Donald Trump said Monday that he is not "personally" bothered by recent short-range missile tests that North Korea conducted this month, breaking with Japanese Prime Minister Shinzo Abe, who is hosting the president on a four-day state visit full of pageantry.

Standing beside Trump at a news conference after hours of talks, Abe disagreed with the U.S. president, saying the missile tests violated U.N. Security Council resolutions and were "of great regret." Abe, who has forged a strong friendship with Trump and agrees with him on many issues, is concerned because the short-range missiles pose a threat to Japan's security.

Trump was invited to Japan to be the first world leader to meet with its new emperor. Despite being far from Washington, he didn't miss the chance to lob another broadside against former Vice President Joe Biden, one of the Democrats seeking to challenge Trump in next year's presidential election. North Korea's Kim Jong Un recently criticized Biden as having a low I.Q. and Trump told the world he agreed with the authoritarian leader's assessment.

Abe is hosting Trump on a state visit designed to highlight the U.S.-Japan alliance and showcase the warm relations between the leaders. During hours of talks at Japan's Akasaka Palace, Trump and Abe also deliberated over economic issues, including trade and Iran, but North Korea's recent firing of short-range missiles emerged as an area of disagreement.

When asked if he was bothered by Pyongyang's short-range missile tests, Trump said: "No, I'm not. I am personally not."

The president has sought to downplay the significance of the missile tests, despite the fact that his own national security adviser, John Bolton, said over the weekend that they violated U.N. resolutions.

Trump continues to hold out hope of eventually getting Kim to agree to give up his nuclear weapons and ballistic missiles, despite two summits he's had with the North Korean leader that produced no concrete pledge to denuclearize the peninsula.

Trump praised Kim, calling him a "smart man" who might have launched the missiles earlier this month to "get attention."

North Korean leader Kim Jong Un supervises a military drill earlier this month. KCNA VIA KNS / AFP - Getty Images

"All I know is there have been no nuclear tests, no ballistic missiles going out, no long-range missiles going out and I think that someday we'll have a deal," Trump said, adding that he is in "no rush."

Trump is correct when he said North Korea has not recently tested a long-range missile that could reach the U.S. But earlier this month, North Korea fired off a series of short-range missiles that alarmed U.S. allies in closer proximity to North Korea, including Japan. The tests broke a pause in North Korea's ballistic missile launches that began in late 2017.

Abe reiterated his previous statement that the tests were carried out in defiance of the U.N.

"This is violating the Security Council resolution," Abe said, adding that, as North Korea's neighbor, Japan feels threatened. "It is of great regret. But at the same time between Kim Jong Un and President Trump a certain new approach was taken and that is something that I pay tribute to."

Earlier Monday, Trump said he backed Abe's interest in leveraging his country's good relations with Iran to help broker a possible dialogue between the U.S. and its nemesis in the Middle East. Abe said he is willing to do whatever he can to help to reduce escalating tensions between the U.S. and Iran.

Trump and Abe discussed the issue earlier Monday. Abe could visit Iran next month.

"Peace and stability of (the) Middle East is very important for Japan and the United States and also for the international community as a whole," Abe said.

The leaders held hours of talks after the U.S. president — at Abe's invitation — became the first world leader to meet Japan's new emperor, Naruhito, who ascended to the throne May 1.

Japanese Prime Minister Shinzo Abe shakes hands with President Donald Trump during a meeting at Akasaka Palace in Tokyo on Monday. Evan Vucci / AP Photo

The meeting with Naruhito and his wife, Empress Masako, was preceded by a grand outdoor welcome ceremony at Japan's Imperial Palace, where Trump walked solo across red carpets, reviewing Japanese troops as the guest of honor.

Trump's official visit also included golf with Abe, presenting a trophy to a sumo wrestling champion and dinner in Tokyo with their wives. The visit came with hours of one-on-one time for Trump and Abe, who has been trying to remain on Trump's good side despite disagreements between them on trade and other issues.

Great morning of golf with Prime Minister @AbeShinzo at Mobara Country Club in Chiba, Japan! pic.twitter.com/EZeJ8znS51 — Donald J. Trump (@realDonaldTrump) May 26, 2019

Trump didn't hold back at the news conference when he was asked about Biden, declaring himself "not a fan."

"Kim Jong Un made a statement that Joe Biden is a low-I.Q individual," Trump said, adding that Kim probably based his assessment on Biden's record and "I probably agree with him on that."

U.S. officeholders usually avoid engaging in politics while on foreign soil, hewing to the adage that politics stops at the water's edge. But Trump's sharp attack on Biden, though his declaration of agreement with Kim, set aside that long-standing norm.

Supporters of President Donald Trump wave flags near the Tokyo hotel where he is staying. CHARLY TRIBALLEAU / AFP - Getty Images

Trump and Abe largely glossed over their difference on trade, despite the potentially crippling tariffs on foreign autos that Trump is threatening to impose on Japan and the European Union. Trump declined to say what Japan would have to do to avoid those tariffs, but complained of an "unbelievably large" trade imbalance with the nation.

Still, he said he expects to reach trade deals at some point with both Japan and China, but wouldn't rush it.

"I think we will have a deal with Japan. Likewise, I think we will have a deal with China sometime into the future," he said. Trump has tried to pressure China by slapping tariffs on hundreds of billions of dollars of Chinese goods.

"I don't believe that China can continue to pay these really hundreds of billions of dollars in tariffs," he said.

CORRECTION (May 27, 2019, 9:30 a.m. ET): An earlier version of this article misstated the security council referred to by Prime Minister Shinzo Abe. It is the U.N. Security Council, not the U.S. Security Council.