The US has said it will impose fresh sanctions on Russia after determining it used nerve agent against a former Russian double agent living in the UK.
Sergei Skripal and his daughter Yulia were left seriously ill after being poisoned with Novichok in Salisbury in March, though they have now recovered.
A UK investigation blamed Russia for the attack, but the Kremlin has strongly denied any involvement.
Russia has criticised the new sanctions as "draconian".
In a statement released on Wednesday, the US state department confirmed it was implementing measures against Russia over the incident.
Spokeswoman Heather Nauert said it had been determined that the country "has used chemical or biological weapons in violation of international law, or has used lethal chemical or biological weapons against its own nationals".