At the rate we are going down hill I give it 50 years at the most.
It MIGHT be argued that the unnatural peace started with Vietnam; however, the outcome in Vietnam had no real effect on American or global security.
Nevertheless, it is certainly a valid point that the US and UK failed to recognize and act upon the real danger of the Soviet Union in the immediate aftermath of World War II.
I would modify your time/event line back to the days of Woodrow Wilson who pushed the idea of an international ruling body and brought into the US the financial persons from Europe to set up the US banking system. The Federal Reserve is only US to the extent of kissing up with a US citizen.