"We are deeply concerned that sanctions have not been imposed on Russia as required by US law stemming from Russia’s use of a chemical weapon against persons living in the United Kingdom," the letter said. "We urge you to immediately impose the legally-mandated additional sanctions against Russia to hold it responsible for such brazen behaviour."
The two congressmen warned in the letter that a failure to respond to "Russia’s unabashed aggression is unacceptable and would necessitate that Congress take corrective action."
Relations between the United Kingdom and Russia hit a new low after the poisoning of former spy Sergei Skripal and his daughter Yulia in Salisbury, England, in March 2018. London claimed they were poisoned with a military-grade nerve agent and blamed the incident on Russia.
Moscow strongly rejected the allegations as groundless, stressing the fact the UK provided no solid evidence of Russia's alleged interference. Apart from this, London rejected Moscow's proposal to carry out a joint investigation of the poisoning and denied Russian officials access to Sergei and his daughter.