MOSCOW — Nuclear weapons are the “only” bulwark preventing the world from slipping into a global war, the Kremlin said on Wednesday amid fears of a fresh multi-country arms race. The last nuclear arms control treaty between Russia and the United States, New START, expired in February, releasing restrictions on the world’s two largest nuclear powers.There have been no signs so far of either side moving to renew or replace the accord, even though both parties agreed to reestablish high-level military talks. At a foreign policy forum in Russia’s capital Moscow, Kremlin spokesman Dmitry Peskov said the global security system…