From the outset of the Czechoslovak crisis the Ceausescu regime asserted that the only basis for relations between states was respect for national independence and sovereignty and a policy of noninterference in another state's internal affairs. The actual invasion, however, marked a reversal for Romanian foreign policy and, although the initial response was one of condemnation and defiance, Romania was put on the defensive. The invasion of Czechoslovakia marked something of a turning point in Romania's relations with COMECON and the Warsaw Pact. The Soviet enunciation of the so-called Brezhnev Doctrine--the concept that the protection of socialism in any communist state is the legitimate concern of all communist states--was intended as a clear warning to the Ceausescu regime. Pressures mounted on Romania to cooperate more fully in the Warsaw Pact and to agree to a supranational planning body within the framework of COMECON. Economic conditions as well as the political and military pressures pushed the Ceausescu regime toward closer cooperation with COMECON, although the Romanians continued to resist the Soviet efforts toward economic integration. As a result of these pressures, the 1968-70 period was one of relative passivity for the Romanians in foreign affairs, although the period was marked by several important events, including the visit of President Richard M. Nixon to Romania in August 1969 and the long-delayed signing of the friendship treaty with the Soviet Union in July 1970. By early 1971 the Ceausescu regime again became more assertive of its independent line in foreign policy. Principles of Foreign Policy According to the 1965 Constitution, the foreign policy of the country is based on strict respect for the principles of national independence and sovereignty, equality of rights, noninterference in internal affairs, and interstate relations based on mutual advantage. The Constitution declares the nation's desire to maintain friendly and fraternal relations with all socialist states as well as to promote friendship and cooperation with states of other sociopolitical systems. Participation in international organizations is directed toward the furthering of peace and international understanding. Spokesmen for the regime have repeatedly asserted these principles as the only acceptable basis for relations between states both within and outside the world communist movement. In contrast to the Soviet position that socialism can only be fully realized by transcending national forms, Romanian policy gives primary emphasis to the distinct requirements of the nation. At the same time, however, Romania recognizes the duties of each socialist state toward cooperative and mutually advantageous relations with all socialist nations and fraternal communist parties.