No terrorist group could set off a nuclear weapon, thank goodness. They contain what are essentially self-destruct mechanisms that prevent unauthorized use. Plus they would be detected coming across the border.
And EMP strikes sound terrifying...but they are not realistic either. The article below is a good one.
Link: https://nationalinterest.org/blog/buzz/world-wont-end-danger-emp-attack-more-fantasy-fact-94681