The article is addressed to an unprecedented crisis of the system and process of nuclear arms control – including nuclear arms reduction and non-proliferation. During a half century history of the practical nuclear disarmament (counting from the 1963 partial nuclear tests ban treaty – PTB) this process has had many ups and downs, but never has it been so deeply deadlocked. Although the two main nuclear treaties are still implemented: the New Strategic Arms Reduction Treaty (START) of 2010 and the Intermediate Nuclear Forces Treaty (INF) of 1987, their future is increasingly uncertain and their validity is eroding, just as that of the Non-Proliferation Treaty (NPT) of 1968 and other agreements in this crucial sphere. For the first time in the last fifty years the world is facing a real threat of totally loosing control over the most destructive weapons created in the history of mankind. What is the most amazing – this is happening half a century after the end of the Cold War, when the hopes emerged that nuclear disarmament would finally become a realistic proposition. Dramatic events in and around Ukraine are badly exacerbating the crisis of nuclear arms control, but they are not its original cause. The article is analyzing the principal reasons of the present crisis: the transforming post-post Cold War world order; Russia’s position and role in the new international environment; the military-strategic, economic and technological developments, which are leading to disintegration of former conceptual premises and mechanisms of nuclear arms control and which are not adapted to the changing objective realities. In conclusion some general proposals are provided with the aim of saving, adopting and enhancing nuclear arms limitation and non-proliferation.