The John Walker spy ring in the ’70′s was ample warning that security was fatally lax, that relatively low-level people could sell or give away the highest security information. Add Aldrich Ames and Robert Hanssen to the mix and the CIA was as porous as any Federal audit involving Halliburton or Blackwater, in other words no controls.
Because the US did not learn the lessons John Walker taught us so painfully and expensively Edward Snowden was able to access, copy and disseminate classified information. Makes no difference that Snowden’s motivations were different, the lessons would be the same.
It’s not as if the US was blindsided or shouldn’t have expected what has happened. Any more than any of us should be surprised that Halliburton will lie, cheat and steal on it’s contracts.