MOSCOW, May 9 (Reuters) - Russian President Vladimir Putin said on Thursday that there was nothing unusual in a planned exercise involving the practice deployment of tactical nuclear weapons in southern Russia along with ally Belarus. Russia said on Monday it would practise the deployment of tactical nuclear weapons as part of a military exercise after what the Moscow said were threats from France, Britain and the United States. "There is nothing unusual here, this is planned work," Putin said, state news agency TASS reported. "It is training." Russia's defence ministry, in its announcement on Monday, explicitly linked the nuclear...