Trudeau visited the Ukrainian embassy in Ottawa Tuesday morning, and personally told the ambassador he was sorry for the remark he made on Radio-Canada's Tout le monde en parle.
The Ukrainian ambassador, Vadym Prystaiko, told reporters waiting outside the building that Trudeau also signed a book of condolences, the first Canadian politician to do so, he noted.
Trudeau was accompanied by his foreign affairs critic, Marc Garneau, but neither spoke to reporters.
Trudeau had tweeted earlier Tuesday, "I just spoke with @PaulMGrod of UCC. Told him I'm sorry to have spoken lightly of the very real threat Russia poses to Ukraine." Grod is president of the Ukrainian Canadian Congress.
Trudeau has come under a barrage of criticism since he said Ukraine should be concerned about Russia's response to the popular uprising in Kyiv, partially because the Olympics host country would be angry it had just lost a hockey game. Russia had been eliminated from Olympic medal contention in men's hockey with a loss to Finland.
The reaction to Trudeau's remark, which sounded flippant, has become intensely political.
Foreign Affairs Minister John Baird, who is in Australia, issued talking points from his office Tuesday. Two of them addressed the situation in Ukraine; the other four were about Trudeau.
The final two points in the release said, "Trudeau apparently thinks the situation in Ukraine is something to joke about. We don't," and, "Once again, Justin Trudeau reminds us that he does not have the judgment to be prime minister. He is in way over his head."
Trudeau may have to further explain his comment about the threat Russia poses to Ukraine, at least to the Russians.
On Tuesday morning in Ottawa, Russia's ambassador to Canada, Georgily Mamedov, warned at a news conference that people shouldn't indulge in rumours about possible Russian intervention in Ukraine. He also said that there would be no Russian troops in Ukraine.
As he began to answer reporters' questions, Mamedov said, "I'm turning serious, because I know you don't appreciate jokes."