One of Donald Trump’s failings as president has been a refusal to face up to Russia’s role in hacking the 2016 election, something American intelligence agencies have testified under oath they know took place. So it is important that when he held his first presidential face-to-face meeting with Vladimir Putin on Friday, Mr. Trump began by raising the interference issue and then reportedly pressed him more than once on Russian involvement during the course of their two-hour-and-15-minute conversation.

Not to do so would have been derelict and would have provided further reason to wonder what sway the Russians may have over Mr. Trump’s White House, as a special counsel investigates Russia’s role in the election and potential collusion by the Trump campaign.

There are important questions, however, about the rest of the exchange, and about whether even now Mr. Trump understands the gravity of Russia’s interference in America’s democratic processes. Secretary of State Rex Tillerson, the only other senior American official in the room, said Mr. Putin denied involvement in the election, as he has in the past, and asked the Americans for proof — a familiar diversionary tactic by Russians caught red-handed. There was no indication that Mr. Trump demanded that Mr. Putin accept responsibility for the hacking or promise that it won’t happen again, either in the United States or in other allied countries, especially Germany, France and the Baltic States, where Russian meddling has been suspected.

If Russia’s foreign minister, Sergey Lavrov, is to be believed, Mr. Trump accepted Mr. Putin’s assurances that he isn’t to blame. And while the White House denied Mr. Lavrov’s version, doubts about the depth of Mr. Trump’s understanding are likely to linger, not least because of Mr. Tillerson’s own description of events. He said Mr. Trump considered the hacking episode to be “simply an intractable disagreement at this point,” thus effectively assigning equal weight to the Russian and American views on the matter.