Alexei Navalny

Despite disagreements on many issues, the president and the Russian leader agreed to extend the only remaining U.S.-Russia nuclear arms control deal.

Russian authorities warned of mass arrests as demonstrators marched in open defiance of the Kremlin and called on President Vladimir Putin to free the jailed opposition leader.

Russian authorities detained the country's top opposition leader after he landed in Moscow on a flight from Berlin. Navalny had been gone nearly five months since he was poisoned last August.

The Russian opposition leader posed as a national security agent during a 45-minute phone call to extract information from a spy who was reportedly involved in Navalny's August poisoning.

During his year-end news conference, the Russian president glibly brushed aside international suspicions that Kremlin agents were behind the attempted assassination of the leading opposition figure.

An investigation by Bellingcat, an Internet research organization, and other media outlets, revealed that for years, Russian agents secretly followed Alexei Navalny.

It is "reasonable to conclude," the EU says, "that the poisoning of Alexei Navalny was only possible with the consent of the Presidential Executive Office."

In an interview, the Russian opposition leader accuses President Vladimir Putin of ordering the attack with the Soviet-era nerve agent Novichok. A Kremlin spokesperson calls the accusation groundless.

A spokeswoman says the Russian opposition leader's bank accounts were frozen and his Moscow apartment "seized" in connection with a libel suit while he was in a coma after poisoning by a nerve agent.

Navalny spent 32 days in Berlin's Charité Hospital, 24 of them in intensive care. Independent lab tests in three countries confirmed he had been poisoned by a Soviet-era nerve agent.