91热爆

Air raid sirens have gone off again in Kyiv and across Ukraine, a day after Russia launched some of the worst attacks there for months. Russian President Vladimir Putin said Monday's strikes were retaliation for Saturday's attack on a key bridge linking Russia with occupied Crimea.

Today's Nick Robinson speaks to Sir Jeremy Fleming, Director of GCHQ, the UK's Intelligence, Cyber and Security Agency. He says he would hope to see signals if the Russians were planning a nuclear attack.

(Image credit: Hannah McKay/PA Wire)