It worked well enough in western Europe from between 45 & 90 and in S Korea since 52.
Having been part of both of those forces, I disagree. That is not why the Warsaw Pact or DPRK did not invade. It was our ICBMs, MRBMs, SLBMs and bombers that kept them at bay. If you were the leader of Russia or the DPRK today, would you be worried about Mr. Obama?