Dive Summary:

• The Three Mile Island nuclear plant in Pennsylvania conducted a drill Tuesday to test emergency response protocol in case of an air strike, the first of such test at a U.S. nuclear plant.
• The drill involved a simulated attack, hundreds of people, plant staff, federal regulators, and even a mock news conference.
• Since 2011, the Nuclear Regulatory Commission has required nuclear plant operators to test such a scenario. 

From the article:

"It concluded that a "hostile action" will pose challenges that aren't covered under existing drills. These include needing to shelter responders from armed or aircraft attack, providing rescue and medical care for large numbers of plant personnel, and operating or repairing the plant when large portions of it are damaged or on fire, the NRC said."