The State Department announced on Wednesday it had determined that Russian Federation was responsible for a chemical attack on Sergei Skripal, a former MI6 informant, in March.
The State Department said in a statement that under the 1991 Chemical and Biological Weapons Control and Warfare Elimination Act, Russia was found to have "used chemical or biological weapons in violation of global law or had used lethal chemical or biological weapons against its own nationals".
The Skripals fell unconscious on a park bench in Salisbury, Wilts, on March 4 after being exposed to a military-grade nerve agent determined to be Novichok.
The new sanctions, details of which were not immediately released, were to take effect following a 15-day Congressional notification period, she said.
PA Wire/PA Images Yulia Skripal, who was contaminated with the nerve agent Novichok along with her father Sergei Skripal.More news: Snap revenue tops estimates due to mobile ad demand
Washington said on Wednesday it would impose fresh sanctions on Russia by the end of August after it determined that Moscow had used a nerve agent against a former Russian agent and his daughter in Britain.
"It is an assault on United Kingdom sovereignty and any such use by a State party is a clear violation of the Chemical Weapons Convention and a breach of global law". The statement anticipated the sanctions would go into effect around August 22 in line with the Chemical and Biological Weapons Control and Warfare Elimination Act of 1991.
One of them, Charlie Rowley, said that he believed the poison came from a bottle of what he thought to be perfume that he found on the ground and gave to his girlfriend, Dawn Sturgess.
Relations between Russia and the West hit a new low, and the United States was among United Kingdom allies that expelled Russian diplomats.
Russia's embassy in London said they had not received any extradition requests over allegations any of its citizens were involved in the novichok poisonings. The US still wants to maintain relations with Moscow, despite the new sanctions.