Several times in the first year of his administration, President Donald Trump wanted to call Japanese Prime Minister Shinzo Abe in the middle of the afternoon. But there was a problem. Midafternoon in Washington is the middle of the night in Tokyo — when Abe would be fast asleep.

Trump’s aides had to explain the issue, which one diplomatic source said came up on “a constant basis,” but it wasn’t easy.

“He wasn’t great with recognizing that the leader of a country might be 80 or 85 years old and isn’t going to be awake or in the right place at 10:30 or 11 p.m. their time,” said a former Trump NSC official. “When he wants to call someone, he wants to call someone. He’s more impulsive that way. He doesn’t think about what time it is or who it is,” added a person close to Trump.