How did a missed email by UPS worker land US F-35 jet parts in China?

A United Parcel Service Inc employee missed an email warning that F-35 parts mustn't pass through certain countries under US arms regulations. The shipment, including a cockpit canopy and weapons-bay door coated with radar-absorbing material, was mistakenly routed through Hong Kong en route from Australia to the US to speed up the delivery. The Pentagon launched investigations after the incident.