As for Mr. Putin, he again brushed off the intelligence agencies’ conclusion that Russia had interfered in the 2016 election on his behalf. A day after making light of it by jokingly telling Mr. Putin in front of cameras “don’t meddle in the election,” Mr. Trump dismissed criticism that he was not taking it seriously enough. “Well, I did say it,” he argued.

He said that the issue came up in his private conversation with Mr. Putin, but noted that the Russian leader had again denied it, an assertion with which he did not publicly quarrel. Indeed, Mr. Trump said he might accept an invitation by Mr. Putin to visit Moscow next spring for the 75th anniversary of the end of World War II.

He also tried to smooth over a rift with President Recep Tayyip Erdogan of Turkey about his country’s purchase of S-400 missile defense systems from Russia. Mr. Trump blamed President Barack Obama’s administration for the dispute and acknowledged that he might have to impose sanctions required by law, but said he hoped to avoid that.

“It’s a problem, there’s no question about it,” Mr. Trump said with Mr. Erdogan at his side as the two prepared to meet behind closed doors. “We’re looking at different solutions.”

But the talks with China, with so much at stake for both sides, were the centerpiece of the trip.

The latest pause in the trade war seemed to be a repeat of sorts of what happened at the last G20 summit meeting, in December in Buenos Aires. There, Mr. Trump and Mr. Xi also met and agreed to postpone further tariffs pending negotiations and more soybean purchases by Beijing. The question is whether the new opening will yield any better result.

The “two sides are highly harmonious, and the areas of cooperation are broad,” Mr. Xi said, according to The People’s Daily, an official Chinese news outlet. “They should not fall into the trap of so-called conflict confrontation, but should promote each other and develop together.”