The US and Russian governments have concluded a high-profile prisoner swap. US basketball star Brittney Griner and Russian arms dealer Viktor Bout were exchanged after weeks of negotiations. Griner was arrested in Moscow in February and charged with drug possession for which she received a nine-year jail term. Bout is a notorious arms dealer who was serving 25 years in the US for conspiring to kill American citizens. Moscow has long sought his release. Our Europe correspondent Simon McGregor-Wood has more.