The fundamental point in fabricating a chain reacting machine is of course to see to it that each fission produces a certain number of neutrons and some of these neutrons will again produce fission.
After America won the Cold War, some believed we had come to the 'end of history,' and budget-cutters celebrated the so-called 'peace dividend.' As a result, we ignored the toxic mixture of militant Islam and terror that ultimately led to 9/11.