RUSSIA HAS warned that it could withdraw from a new nuclear arms reduction pact with the United States if it feels threatened by Washington’s planned missile defence system in central Europe. Foreign minister Sergei Lavrov issued the warning as his president, Dmitry Medvedev, and US counterpart Barack Obama prepared to head to the Czech Republic for tomorrow’s signing of a long-awaited treaty to cut their countries’ arsenals of deployed nuclear warheads by about a third. As Prague ramped up security for the visit of the two leaders, Mr Obama’s administration yesterday unveiled a new policy renouncing the development of new...