When Donald Trump met Chancellor Angela Merkel of Germany earlier this month, he put on one of his most truculent and ignorant performances. He wanted money -- piles of it -- for Germany's defense, raged about the financial killing China was making from last year's Paris climate accord and kept "frequently and brutally changing the subject when not interested, which was the case with the European Union."

This was the summation provided to me by a senior European diplomat briefed on the meeting. Trump's preparedness was roughly that of a fourth grader. He began the conversation by telling Merkel that Germany owes the United States hundreds of billions of dollars for defending it through NATO, and concluded by saying, "You are terrific" but still owe all that dough. Little else concerned him.

Trump knew nothing of the proposed European-American deal known as the Trans-Atlantic Trade and Investment Partnership, little about Russian aggression in Ukraine or the Minsk agreements, and was so scatterbrained that German officials concluded that the president's daughter Ivanka, who had no formal reason to be there, was the more prepared and helpful. (Invited by Merkel, Ivanka will attend a summit on women's empowerment in Berlin next month.)

Merkel is not one to fuss. But Trump's behavior appalled her entourage and reinforced a conclusion already reached about this presidency in several European capitals: It is possible to do business with Trump's national security adviser, Lt. Gen. H. R. McMaster, with Secretary of Defense Jim Mattis, and with Secretary of State Rex Tillerson, but these officials are flying blind because above them at the White House rages a whirlwind of incompetence and ignorance.