In the light of the interaction of the perspective of two-level games with the model of bureaucratic politics and the neo-institutionalist perspective on ideas, the main purpose of this research is to explain why the U.S. and Russia decided not to comply fully and effectively with the action plan of 13 practical steps on nuclear disarmament, agreed at the Review Conference of the Non-Proliferation Treaty in 2000. The hypothesis indicates that changes of political and strategic decisions of major nuclear powers in relation to international cooperation in the area of arms control and nuclear disarmament were motivated by changes of the preferences of members of the Executive for a greater role of nuclear offensive arms and defensive systems in security policy, the use of more flexible instruments for managing violence and the possible use of nuclear weapons on the battlefield. Such changes occur in the light of the interaction between the possibility of reversion of cooperation with traditional nuclear powers and the strengthening of rogue states and terrorist organizations at the international level and the need to meet the preferences of Legislature majority and interest groups on strategic security issues at the domestic level. It is also necessary to consider changes in the occupation of key positions in foreign and security policy formulation. Those powers are distributed by domestic institutions. Changes in the beliefs of the main political actors - with more assertive and conservative ideas - hampered international cooperation on the steps of the action plan.