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 worldwide law or had used lethal chemical or biological weapons against its own nationals".
The U.S. announced new sanctions on Russia Wednesday, saying it's made a final determination that Vladimir Putin's government was responsible for the March 4 nerve-agent attack on former double agent Sergei Skripal and his daughter in the United Kingdom.
She said sanctions would take effect on or around August 22, but did not specify the nature of the new punitive measures.
In late March, Trump ordered 60 more Russian diplomats expelled from the USA as part of a global response to the attack - a response that included similar expulsions of diplomats from other nations checking Russia.
There would, however, be exemptions for space flight activities, government space cooperation, and areas covering commercial passenger aviation safety, which would be reviewed on a case by case basis, the official added.
"The strong worldwide response to the use of a chemical weapon on the streets of Salisbury sends an unequivocal message to Russian Federation that its provocative, reckless behaviour will not go unchallenged".
Two more people, Charlie Rowley and Dawn Sturgess, later came into contact with the lethal substance and were hospitalised.
London and its allies have accused Moscow of trying to kill the Skripals and says the two cases are likely linked.
The Government has been consistent in pointing the finger of blame at Moscow for the poisoning using novichok - a military-grade nerve agent developed by the former Soviet Union.
Last month, British Prime Minister Theresa May urged Trump to raise the issue of the poisonings when he met with Russian President Vladimir Putin in Helsinki, although it remained unclear whether the subject came up in their talks.
Paul said the letter "emphasised the importance of further engagement in various areas including countering terrorism, enhancing legislative dialogue and resuming cultural exchanges".