Russia and the US on Tuesday dismissed suggestions of a “quid pro quo” deal on Washington’s missile defence plans for central Europe. But, speaking after it was revealed that Barack Obama had sent Dmitry Medvedev a letter discussing the topic, the countries’ presidents stressed improved prospects for co-operation.

The US says missile defence bases in Poland and the Czech Republic would be intended to neutralise threats from Iran but Russia, which has long opposed the plan, insists they would affect its nuclear deterrent.