Big increases in government spending associated with the GreatSocietyprograms, the war on poverty, the Vietnam War, and the Space Race, resulted in large deficits (by 1971 standards of course).
Johnson was hoping that the worst would not come true, that it would remain a short war, and he feared that that if the true economic cost of the war became visible to the naked eye, he would lose his GreatSocietyprograms.
But we drew another conclusion, both from the New Deal experience and especially the GreatSociety era which expanded on it, that has proved to be less defensible: that social programs of all types can be managed or funded by government to good effect.