WEST PALM BEACH, Fla. — As negotiations over a summit meeting with the ruler of North Korea accelerate, President Trump on Sunday disputed any suggestion that he had made too many concessions at the outset of an unpredictable and potentially volatile diplomatic exercise.

From his Florida estate, Mr. Trump took to Twitter to criticize Chuck Todd, the host of “Meet the Press,” who questioned on that program and an earlier broadcast whether the president had gotten anything in return for the “huge gift” he had given the North Korean leader, Kim Jong-un, by agreeing to meet with him.

On “Meet the Press,” Marc Short, the White House legislative affairs director, had an answer teed up — that the North Koreans had given the United States “an agreement to stop testing” nuclear weapons.

But from his Twitter account, the president chose to address Mr. Todd directly.

“Sleepy Eyes Chuck Todd of Fake News NBC just stated that we have given up so much in our negotiations with North Korea, and they have given up nothing,” Mr. Trump wrote. “Wow, we haven’t given up anything & they have agreed to denuclearization (so great for World), site closure, & no more testing!”