The military industrial complex of which President Dwight D. Eisenhower spoke is one and the same threat noted by President Kennedy in his speech regarding secret societies. It is the private control of government by covert means, by secret influence and unaccountable hands.
This means the arms industry in particular, which stands to make money with every U.S. war. In practice, it was and is manifested by multinational armaments industries, military, government and private interests dedicated to the fomenting of war. Halliburton encompasses every item above. It produces arms and war supplies. It's non-combat operations profit indirectly from wars. It has reached the very limits of Presidential influence and control.
The smoking gun is the presence of no-bid contracts and the initiation of indefinite wars, such as the cold war and the "war on terror".