Donald Trump once again praised Vladimir Putin, but this time, the kudos came after he released a friendly letter from the Russian leader — and mere hours after the president-elect acknowledged that he's willing to enter into a nuclear arms race.

Putin wrote the Christmas greeting to Trump more than a week ago on Dec. 15, and said he wants to bring U.S.-Russian "collaboration on the international scene to a qualitatively new level."

Trump confirmed Friday that he received a "very nice letter" from Putin in a two-line statement sent to the press, and said the Russian president's "thoughts are so correct."

"I hope both sides are able to live up to these thoughts," Trump added, "and we do not have to travel an alternate path."

What Trump means by "an alternate path" is unclear, but the letter's release comes amid increased buzz over the nuclear issue: Trump tweeted on Thursday that America must "expand" its nuclear capability.

The United States must greatly strengthen and expand its nuclear capability until such time as the world comes to its senses regarding nukes — Donald J. Trump (@realDonaldTrump) December 22, 2016

Then, on Friday morning, he said in a statement to MSNBC's "Morning Joe" that he's supportive of an arms race.

"Let it be an arms race. We will outmatch them at every pass and outlast them all," Trump said.

Putin had boasted about the strength of Russia's nuclear arsenal before Trump's tweet Thursday.

When Putin and Trump will officially meet face to face is unclear.

In response to a question from NBC News at his annual, nearly four-hour-long press conference Friday, Putin did not give a timeline. But when it happens, he said, the normalization of U.S.-Russian relations will be on the agenda, adding that current relations have hit rock bottom.