Moscow has said a move towards a missile defence strategy would violate the 1972 Anti-Ballistic Missile Treaty.

CNN: Powell in Berlin after Moscow talks

Russia appears close to agreeing a deal to revise the anti-ballistic missile treaty - lifting its objections to an American system of missile defence.

BBC: Shanghai showcase

Their Aegis missile defence system, deployed to protect American carrier groups, is designed to track a missile's trajectory from launch.

ECONOMIST: Wary detente between China and America