WASHINGTON — “Errrrrgggggahhhh,” said Senator Pat Roberts, Republican of Kansas, when asked his opinion of President Trump’s harsh words for the United States’ NATO allies on Wednesday. “I haven’t had time to sift through all that.”

“All that” would be Mr. Trump’s widely reported fusillade against the North Atlantic Treaty Organization over breakfast in Brussels with Jens Stoltenberg, the alliance’s secretary general.

“Frankly, many countries owe us a tremendous amount of money for many years back, where they’re delinquent, as far as I’m concerned, because the United States has had to pay for them,” Mr. Trump said, mischaracterizing how the commitments for NATO military spending work.

Then, as members of the delegation stared into their orange juice, Mr. Trump told them that Germany was a “captive” of Russia because it receives 9 percent of its natural gas from the country — though Mr. Trump erroneously said it was 70 percent.