The Biden administration on Tuesday imposed sanctions to punish Russia for what it described as Moscow's attempt to poison opposition leader Alexey Navalny with a nerve agent last year in President Joe Biden's most direct challenge yet to the Kremlin.

The move marked a sharp turn away from former President Donald Trump's reluctance to confront Russian President Vladimir Putin.

Seven senior members of the Russian government would be blocked from accessing their financial assets in the U.

S.

But it was unclear whether the seven had US assets, making it hard to judge whether the sanctions were more than symbolic.

White House press secretary Jen Psaki.

It was not meant to be a silver bullet or an ending to what has been a difficult relationship with Russia.

We expect the relationship to continue to be a challenge.

We're prepared for that and we're neither seeking to reset our relations with Russia, nor are we seeking to escalate.

New export restrictions were also placed on businesses and other entities associated with Russia's biological and chemical agent production.

Navalny, a Putin critic and political opponent, became ill on a flight in Siberia in August and was airlifted to Germany, where doctors concluded he had been poisoned with a nerve agent.

The Kremlin has denied any role in his illness and said it had seen no proof he was poisoned.

Navalny returned to Russia in January and was jailed February 2nd for parole violations on what he said were politically motivated charges.

We also reiterate our call for the Russian government to immediately and unconditionally release Mr Navalny.

The U.

S sanctions are in concert with similar ones imposed by the European Union Tuesday.

The Interfax news agency reported that Russian Foreign Minister Sergei Lavrov said earlier in the day that Russia would respond in kind to any new U.

S sanctions over Navalny.