Stephen Sackur speaks to the former head of Russian Railways, Vladimir Yakunin. For the past 17 years Vladimir Putin has ruled Russia - as president or prime minister. But he hasn't done it alone. He has beenbacked by a coterie of trusted associates, connected through past ties in St Petersburg, or in the KGB or in business. Yakunin was part of President Putin's inner circle, so much so the US made him a target of sanctions after the invasion of Crimea. Are cracks showing in the Putin project?