Russian President Dmitry Medvedev says, a new arms race could begin in the next decade if NATO and Moscow fail to agree on a joint missile shield. In his annual speech to the nation, he said he had advocated a full fledged joint mechanism of co-operation at a recent NATO-Russia summit.After the NATO-Russia summit in Lisbon earlier this month, NATO chief Anders Fogh Rasmussen announced that Russia had agreed to co-operate on NATO's programme to defend against ballistic missile attacks.