Russia, which vigorously objected to the Bush-era missile defence shield plan in Europe, has welcomed as "responsible" the move by Barack Obama, the US president, to scrap his predecessor's plan.

But it is not yet clear if Russia will reciprocate by halting the planned delivery of sophisticated anti-aircraft systems to Iran that would enable Tehran to shoot down any US or Israeli planes seeking to attack its nuclear facilities.

Rob Reynolds asks what, if anything, Obama will get in return from the Kremlin for changing the missile shield plan.