President Trump met with South Korean President Moon Jae-in on Tuesday. (Saul Loeb/AFP/Getty Images)
Daniel W. Drezner is a professor of international politics at the Fletcher School of Law and Diplomacy at Tufts University and a regular contributor to PostEverything.

On Saturday, President Trump spoke with his South Korean counterpart Moon Jae-in. According to my Post colleagues David Nakamura and Carol Leonnig, Trump is trying to understand why his new BFF Kim Jong Un sounded so snippy the week before:

On the call, which lasted less than 30 minutes, Trump sought Moon’s interpretation of Pyongyang’s shift to a harder-line position last week, a sharp contrast to the more positive and constructive tone after Moon met with North Korean dictator Kim Jong Un last month, according to a senior U.S. official with knowledge of the conversation.

North Korea’s actions in recent days, including its cancellation of a working-level meeting with South Korean officials and a threat to call off Kim’s summit with Trump on June 12, have alarmed the Trump administration and created new complications in the preparations, with just over three weeks left. An advance team from the United States is in Singapore to work out logistics, Trump administration officials said.

There are two interesting facts buried within this story. The first is the fact that Trump felt the need to speak with Moon just a few days before he saw Moon in person this week in Washington. This is a little bit unusual.

The second fact is still more unusual:

Inside the West Wing, aides said Trump was upset by Kim’s first visit to China in March, ahead of which Beijing did not notify the White House. The president reacted angrily in a national security meeting, according to an administration official, and Xi later wrote a letter assuaging Trump.

Trump’s concerns about China’s influence on the summit with Kim were reflected in the president’s tweet last week in which he declared that his administration was looking at ways of potentially assisting ZTE, a Chinese phone maker that has struggled in the wake of U.S. economic sanctions.

This tidbit is just odd. Anyone who read any backgrounder on North Korea would know that Kim was highly likely to meet with Xi. The idea that Kim would go into a summit with Trump without at least consulting North Korea’s most important quasi-ally borders on the absurd. But it is not surprising that Trump would be unaware of this fact.

I fear that The Fix’s Callum Borchers already identified the explanation: The only briefing Trump gets is whatever he reads/hears in the press. As Time’s Brian Bennett and Tessa Berenson reported last week, the president has not exactly been fully briefed on the matter:

President Donald Trump hasn’t set aside much time to prepare for meeting with Kim Jong Un, a stark contrast to the approach of past presidents.

“He doesn’t think he needs to,” said a senior administration official familiar with the President’s preparation. Aides plan to squeeze in time for Trump to learn more about Kim’s psychology and strategize on ways to respond to offers Kim may make in person, but so far a detailed plan hasn’t been laid out for getting Trump ready for the summit.

I do not blame Trump’s staff for leaking their extreme skepticism to the news media in recent days. Clearly, Trump wants this summit to go forward, so he can do something no other president has done. Just as clearly, he is doing zero prep work and therefore overreacting to every shift in the news cycle.