Poisoned relations: UK sanctions Russia over nerve agent attack

Following the ultimatum given to Russia, Theresa May has confirmed the expulsion of 23 Russian diplomats. But this seems to be only the start. The UK prime minister is promising more retaliation against Moscow for the unleashing of a military-grade nerve agent on British soil. How far can she go in holding the Kremlin responsible for the attack on former double agent Sergei Skripal and his daughter? Will Theresa May have the backing of Donald Trump and her European allies?