The US has announced sanctions on Russians over the poisoning of opposition leader Alexei Navalny.
The sanctions will target seven senior Russian officials and 14 entities involved in chemical production, US officials told reporters.
They said US intelligence had concluded that the Russian government was behind the near-fatal nerve agent attack on Navalny in Siberia last year.
He is the most high-profile critic of President Vladimir Putin.
Moscow denies involvement in his poisoning and disputes the conclusion, by Western weapons experts, that the nerve agent Novichok was used.
What did the US officials say?
Speaking to reporters during a conference call, they said the measures were being co-ordinated with the European Union, which is expected to announce similar steps.
They are the first sanctions imposed on Russia by the administration of President Joe Biden.
He has taken a tougher stance than his predecessor Donald Trump towards President Putin.
After phoning his Russian counterpart last month, Mr Biden said he had made it clear the days of the US “rolling over in the face of Russia’s aggressive actions, interfering with our elections, cyber-attacks, poisoning citizens are over”.
Who is Alexei Navalny?
An anti-corruption campaigner, he has long been the most prominent face of Russian opposition to Mr Putin’s rule.
The 44-year-old blogger has millions of followers on social media. He managed to get some of his supporters elected to councils in Siberia in 2020.
Navalny was poisoned and fell into a coma during a flight to Siberia last August. He was airlifted to Germany, where he recovered. In January he decided to return to Russia and was arrested on arrival.
A court last month found that Navalny had violated the terms of his probation over an earlier embezzlement case. His suspended sentence was turned into an actual prison term of two-and-a-half years.
Last week he was sent from detention in Moscow to a penal colony to serve out the sentence.
President Biden and EU leaders have called for his immediate release.