The US exports technology around the world and the US is also wary about domestic threats (they will not admit this). Widespread access to E2E encryption thwarts global surveillance and legitimate law enforcement (imagine insider trading), both inside and outside the country, and weakens America's national power. She feels she needs every advantage right now.

Here's one article that mentions E2E encryption: https://foreignpolicy.com/2015/04/23/defense-department-sili...