Abstract. Signing and ratification of the new Strategic Arms Reduction Treaty (START) by the U.S. and Russia in 2010–2011 inspired the adherents of interaction between two nations on arms reduction in both states, as well as in Western Europe and the rest of the world. Due to the new Treaty, in 2010 the summit of the leading states on nuclear materials and technologies security took place; a regular conference on the Nuclear Non-Proliferation Treaty (NNPT) scrutiny went successfully. Many a one thought that after 10 years of stagnation it set the wheels in motion, and the world free from nuclear arms that the Presidents of both countries called for became a closer reality. But by the end of 2011, the optimism gradually gave place to a growing pessimism. During the ratification of the Treaty of Prague in Winter 2010–2011, both Parliaments raised reservation clauses as requirements for execution of the Treaty – almost diametrically opposed, and incompatible with the prolongation of negotiations on arms reduction. In the present article, the attempt is made to sort out the reasons of such drastic strategic "volte-face", and to suggest both ways out of deadlocks and ways to restore progressive advance in the matter of arms control, which is a binding condition for non-proliferation regimes enhancement.