The most powerful segment of the US economy was dependent upon the Cold War and when it was won conditions were not the same as after the defeat of Germany and Japan. After WW2 there was more upside in reconstruction than a rematch, this time no contracts for rebuilding were on offer and there was no new enemy to declare. "Terrorists" are in reality a very small and cheap adversary and linking them to more lucrative nation target is neither easy nor sustainable.
The same case exists with the Soviet/Russian governments, which have been in a state of war for the same period. With much tighter control than even the US wields over its corporate media, the Russian government makes war not only a business but headline news and entertainment, especially when other state controlled economic enterprises are failing.
Thus unless a credible new enemy is developed both military dependent governments need to maintain a level of antagonism in order to function.