As U.S. President Donald Trump met with Japanese Prime Minister Abe Shinzo in Japan over the weekend, differences over trade and North Korea lingered below the surface.

President Trump’s visit to Japan over memorial day weekend was marked by displays of camaraderie with Japanese Prime Minister Abe Shinzo, including golf, a barbecue dinner, and a sumo wrestling match. But while the leaders demonstrated strong ties on the surface, significant differences in trade and North Korea policy underlied their meeting.

Japan and US Struggle to See Eye to Eye

The most significant difference came in response to North Korea’s recent ballistic missile tests, which the Japanese prime minister called “extremely regrettable” and a “breach of U.N. Security Council resolutions.” While Japan has called for stricter enforcement of U.N. resolutions regarding its nuclear-armed neighbor, President Trump took a non-critical tone on the missile tests, tweeting Saturday:

“North Korea fired off some small weapons, which disturbed some of my people, and others, but not me. I have confidence that Chairman Kim will keep his promise to me, & also smiled when he called Swampman Joe Biden a low IQ individual, & worse. Perhaps that’s sending me a signal?”

Shortly before his tweet, President Trump’s national security adviser John Bolton told reporters there was “no doubt” North Korea’s missile test breached United Nations Security Council resolutions and said the administration would continue to enforce tough sanctions on Kim Jong Un’s regime.

After President’s Trump was widely criticized for lauding Kim Jong Un’s disparaging remark of America’s former vice president, NBC host Chuck Todd questioned Press Secretary Sarah Huckabee Sanders, “Can you explain why Americans should not be concerned that the President of the United States is essentially siding with a murderous, authoritarian dictator over a former vice president of the United States?”

“The president’s not ‘siding’ with that. But I think they agree in their assessment of former vice president Joe Biden. Again, the president’s focus in this process is the relationship he has, and making sure we continue on the path to denuclearization,” responded Sanders.

One of Vice President Biden’s aides spoke to ABC News about the president’s tweet, saying, “I would say the tweet speaks for itself, but it’s so unhinged and erratic that I’m not sure anyone could even say that with a straight face. The spelling error was not the main problem with the first one,” referring to Trump’s spelling the former vice president’s name “Bidan” in the first version of the tweet.

Do Trade Issues With Japan Loom?

Trade was another issue discussed between the leaders, as President Trump met with Japanese business executives and spoke of what he perceived to be a trade dynamic favorable to the Japanese.

“I would say that Japan has had a substantial edge for many, many years, but that’s okay. Maybe that’s why you like me so much,” the president said. President Trump recently declared imported vehicles a threat to national security and threatened to impose tariffs that would devastate Japanese auto manufacturers.

The president said trade negotiations would be on hold until Japanese elections in July, but expressed optimism for future bilateral agreements.

“With this deal we hope to address the trade imbalance, remove barriers to United States exports and ensure fairness and reciprocity in our relationship. And we’re getting closer,” said President Trump.