The USA has said it will impose new sanctions on Russia over the poisoning of two people in Salisbury.
Sergei Skripal was a former Russian double agent living in the UK. Along with his daughter Yulia, he was left seriously ill after being poisoned by the nerve agent Novichok in March.
The UK blames Russia, but the Russian government strongly denies any involvement.
But what are sanctions and how do they work?
Imran Rahman-Jones 