President-elect Donald Trump praised President Vladimir Putin for refraining from tit-for-tat expulsions of Americans in response to U.S punitive measures over alleged Russian interference in the November election.

Putin's decision came despite the foreign ministry asking him to send home 35 U.S diplomats after President Barack Obama had expelled the same number of Russian staff.

Trump's intervention -- in a tweet -- however illustrated the shifting political tide in Washington, barely three weeks before the Republican is due to succeed Obama at the White House.

"Great move on delay (by V. Putin) - I always knew he was very smart!" the incoming U.S president wrote.

Russia's embassy in Washington quickly retweeted the comment, which Trump pinned so it would appear at the top of his feed for several hours.

Trump's tweet enraged his Democratic foes as well as some members of his own Republican Party.

The alleged hacking of the US presidential election in November outraged Obama, culminating in the expulsions and other sanctions.

But outlining why he would not retaliate, Putin cited Trump's imminent accession.

"We will not expel anyone," Putin said in a statement, also inviting children of U.S diplomats to a holiday party at the Kremlin.

Instead, Moscow will plan its next steps "based on the policies pursued by the administration of president Donald Trump," while warning that the Kremlin reserves the right to respond.

The Russian leader chided the outgoing Obama for "unfriendly steps" amounting to "a provocation aimed at further undermining Russian-American relations."

Putin confirmed Moscow is pinning its hopes on Trump to help rebuild ties -- which have plunged to their lowest point since the Cold War -- when he takes office next month.

Putin ended his statement on the sanctions by wishing Obama and Trump a Happy New Year, separately congratulating the U.S president-elect in a New Year message.