To sustain the existence of the South Vietnam regime, Nixon massively increased American military aid. Yet in 1975 the regime's army quickly collapsed when regular army units of the Communist forces attacked. "Moral disintegration alone can explain why an army three times the size and possessing more that five times the equipment of the enemy could be as rapidly defeated as the ARVN was between March 10 and April 30, 1975," commented Joseph Buttinger. American military deaths from the war were over 47,000, with 153,000 wounded. South Vietnamese military losses (using low figures) were about 110,000 killed and 500,000 wounded. Communist Vietnamese military losses were later announced: 1,100,000 killed and 600,000 wounded. Hanoi also estimated that total civilian deaths from the war, 1954 to 1975, were 2,000,000. According to Spencer C. Tucker, "The number of civilians killed in the war will never be known with any accuracy; estimates vary widely, but the lowest figure given is 415,000."