The victory of the Vietnamese Communists in May 1975 was a w atershed in the contem porary h isto ry of the region and it was an event to which subsequen t developments w ere, one way or an o th er, re la ted . For the Soviet Union, the Vietnamese v ictory signified opportun ity and the end of a period when its diplomacy was unable to make headway against regional resistance th a t was largely b u t not en tirely bo lstered by the continuing p resence of the United S ta tes. American defeat in Indochina inaugura ted a phase of u n ce r­ ta in ty which the Soviet leadership had in tended to exploit upon the assum ption th a t impediments to Soviet penetration arose as a consequence of the American position within the region. Ultimately, how ever, the Soviet Union failed to con­ v e rt expectations into tangible political successes which showed th a t the region itse lf had erected b a rr ie rs against the assertion of Soviet influence in a way which continued to confirm the undeniable irre levance of the Soviet Union to the aspirations of the region. R ather than o p p ortun ity , the Soviet Union found opposition which narrow ed Soviet a tten tion to Vietnam in the context of the em erging d ispute with China.