Russia-Ukraine crisis: British nationals told to leave Ukraine

British nationals have been urged by the foreign office to leave Ukraine immediately "while commercial means are still available".

This comes as the US national security advisor warned that Russia could invade Ukraine before the end of the Winter Olympics.

Jake Sullivan said Americans should leave Ukraine "in the next 24 to 48 hours” adding that the threat is now immediate enough that this is prudent.

We spoke to former US National Security Council adviser Fiona Hill.