Why did United Nations' Tero Varjoranta resign??

Was he or his family threatened with bodily harm?  Was he blackmailed?  Did the PTB have some discriminating information on him that they threatened to disclose if he didn't resign?  What's going on????

From TruePublicaUK
IRAN – America’s Playbook of War Reopens

Almost universally missing from the UK’s mainstream media coverage of the current Iran crisis is the fact that the UN’s most senior nuclear inspector has unexpectedly ‘resigned.’

AP News 12/05/18: The U.N.’s nuclear watchdog says its top inspector has quit with immediate effect, just as the agency’s work in Iran is once again in focus. The International Atomic Energy Agency didn’t give a reason for the sudden resignation of Tero Varjoranta, stating Saturday that it doesn’t comment on confidential personnel matters. The move comes just days after U.S. President Donald Trump announced the United States would withdraw from the 2015 Iran nuclear accord designed to keep Tehran’s atomic weapons program in check.

The significance of this resignation is historical..........