President Vladimir Putin

Updated at 10:20 a.m. ET

In his marathon year-end news conference, Russian President Vladimir Putin projected confidence and defiance on a range of issues — and vehemently denied government involvement in the recent poisoning of Russian opposition leader Alexei Navalny.

On Thursday, Putin appeared during the latest iteration of a Q-and-A that regularly tops four hours, which he has led for nearly two decades running.

Updated at 3:30 p.m. ET

Russian President Vladimir Putin has congratulated Joe Biden on his win in the 2020 U.S. presidential election, becoming one of the last world leaders to do so. Hours afterward, other leaders who had held off in recognizing Biden's victory — Brazilian President Jair Bolsonaro and Mexican President Andrés Manuel López Obrador — also congratulated Biden.

Updated at 5:00 p.m. ET

Russian hackers working for the Kremlin are believed to be behind breaches of U.S. government computer systems at the departments of Treasury, Commerce and Homeland Security that may have lasted months before they were discovered, according to U.S. officials and media reports.

Russian voters have overwhelmingly backed a referendum on constitutional changes that includes a provision allowing President Vladimir Putin — who has already served for some two decades — to remain in power until 2036.

With nearly all of the ballots counted, the tally for the voting that has taken place over a full week showed a 78% "yes" vote, according to Russia's Central Election Commission. The commission estimated the turnout was 65% of eligible voters.

The opposition accused the government of rigging the vote.