U.S. President-elect Donald Trump on Friday praised Russian President Vladimir Putin for refraining from retaliation in a dispute over spying and cyber attacks, in another sign that the Republican plans to patch up badly frayed relations with Moscow.

Putin earlier on Friday said he would not hit back for the U.S. expulsion of 35 suspected Russian spies by President Barack Obama, at least until Trump takes office on Jan. 20.

"Great move on delay (by V. Putin) - I always knew he was very smart!" Trump wrote on Twitter from Florida, where he is on vacation.

Obama on Thursday ordered the expulsion of the Russians and imposed sanctions on two Russian intelligence agencies over their involvement in hacking political groups in the Nov. 8 U.S. presidential election.

"We will not expel anyone," Putin said in a statement, adding that Russia reserved the right to retaliate.

"Further steps towards the restoration of Russian-American relations will be built on the basis of the policy which the administration of President D. Trump will carry out," he said.

In a separate development, a code associated with the Russian hacking operation dubbed Grizzly Steppe by the Obama administration has been detected within the system of a Vermont electric utility, the Washington Post reported on Friday, citing unnamed U.S. officials.

The Russians did not actively use the code to disrupt operations of the utility, the officials told the Post, but penetration of the nation's electrical grid is significant because it represents a potentially serious vulnerability.

More at Reuters.