Afghanistan and expansion to dominate Nato summit

April 1: Heads of government from Nato members will gather this week in Bucharest for the military alliance's annual meeting. But this year's summit will be the largest in recent times - and possibly one of the thorniest. At stake are questions about member countries' commitment to Nato's operations in Afghanistan and, perhaps trickier still, a decision on inviting Georgia and Ukraine into the alliance. James Blitz, diplomatic editor, talks to three of the key players about their aims.