You're right about following orders, but they do participate in the "power elite." Back when Mills wrote (the mid-1950s), we had people like the "mad bomber" (Curtis Lemay) in the Pentagon. He pushed for nuclear war with the USSR and was listened to (though his position didn't win).
The Pentagon people in general are are allied with the capitalists of the military industries, to form the famous military-industrial complex. -- Jim Devine / "There can be no real individual freedom in the presence of economic insecurity." -- Chester Bowles