WASHINGTON — President Trump’s appetite for a meeting with President Vladimir V. Putin of Russia, his aides say, was whetted by his talks with Kim Jong-un, the leader of North Korea, two weeks ago. But it is precisely that encounter that is stirring unease among foreign policy experts, including some in his own administration.

They worry that Mr. Trump will make the same kinds of concessions to Mr. Putin when they meet in Helsinki, Finland, on July 16 that he made to Mr. Kim in Singapore, tilting a relationship that has already swung in Russia’s favor.

In the past few weeks alone, Mr. Trump has called for Russia to be readmitted to the Group of 7 industrial powers, suggested it has a legitimate claim to Crimea because a lot of Russian speakers live there and continued sowing doubts about whether Moscow meddled in the 2016 presidential election — or if it did, whether the sabotage actually benefited Hillary Clinton.

In Singapore, Mr. Trump emerged from a lunch of sweet and sour crispy pork with Mr. Kim to declare he had solved the nuclear crisis with North Korea, even though the North conceded nothing on its weapons and missile programs. Mr. Trump also canceled joint military exercises with South Korea, a concession long sought by Pyongyang.