Current and former American officials have said that phone records and intercepted calls show that members of Mr. Trump’s 2016 presidential campaign and other Trump associates had repeated contacts with senior Russian intelligence officials in the year before the election.

Former diplomats and Russia specialists say it would have been absurd and contrary to American interests for the Trump team to avoid meetings with Russians, either during or since the campaign.

John R. Beyrle, the United States ambassador to Moscow from 2008 to 2012, said he feared that “we’re beginning to out-Russian the Russians” by treating all contacts as suspicious. When he returns to Russia now, he said, “this real anti-Western, anti-American frenzy” prompts some old acquaintances to refuse to meet him because they worry about being tagged as too friendly to the United States.

“That’s the last behavior we should model — that simply meeting with a Russian official is wrong, without any knowledge of what was said,” Mr. Beyrle said.