US Secretary of State Mike Pompeo says there is a “substantial chance” that the suspected poisoning of Russian opposition figure Alexey Navalnyi was ordered by senior officials in Moscow.
Mr. Pompeo said the US was evaluating how it would react.
NATO and Germany say there is “evidence beyond doubt” that Mr Navalny was attacked with a Novichok nerve agent.
Mr. Pompeo’s remarks contradict President Donald Trump’s refusal to condemn Moscow.
Last month, Mr. Navalny was taken from Berlin to Russia after falling ill on a flight from Siberia to Moscow.
The 44-year-old was brought out of an induced coma earlier this week, with doctors at the Charity Hospital in Berlin stating that she was responding to oral stimuli, but that “to speculate on the possible long-term effects of her severe poisoning” It was too early for “.
Mr. Pompeo made his remarks in an interview with conservative American commentator Ben Shapiro, who asked if the apparent attacks on his political opponents would have any implications for the Russian government.
The Secretary of State said that the EU as well as the US had made it clear to Russia that “our expectations are that they will hold this accountable accountable. We will try our best to come to the conclusion of who was responsible”.
“I think people around the world will see this kind of activity for what it is,” he said. “And when they see an attempt to poison a dissident, they believe that there is sufficient probability that it actually came from Russia”.
He said that “the world has matured and understood how these common countries work, and it will prove costly for the Russians.”
Mr Pompeo declined to say what the US would react to as “not wanting to appear before the president”, but said Washington would “do its part to reduce the risk that things like this happen again”.
President Trump has given no indication of how the US will respond to the poisoning on Saturday: “I don’t know what really happened. I think it’s sad, it’s terrible, it shouldn’t happen . We didn’t have any. Proof yet but I’ll have to take a look.
NATO has called on Russia to disclose its Novichok Nerve Agent program on international monitors. General Secretary Jane Stoltenberg said the members were united in condemning the “horrific” attack on Mr Navalny.
On Wednesday, Russia’s foreign ministry called the German ambassador to protest what he called “baseless allegations and ultimatums against Russia” and use the Navalnyi case on Berlin “as an excuse to discredit his country” ” Told.
Mr. Navalny is an anti-corruption campaigner who for a long time was the most prominent face of opposition to President Vladimir Putin in Russia.
His supporters believe that his tea was served at Tomsk Airport on 20 August. He became ill during the flight, and the plane made an emergency landing in Omsk to take him to the hospital. The Russian authorities were persuaded two days later to allow them to airlift in Germany.
A nerve agent from the Novichok group identified in the Navy case in Germany was also used to poison former spy Sergei Skripal and his daughter in Salisbury, England. They both survived but a local woman, Don Sturges, died after being exposed to the poison.
Britain accused Russia of military intelligence of carrying out the attack in Salisbury. As part of a coordinated response, 20 countries expelled more than 100 Russian diplomats and spies. Russia denied any involvement.