San Diego's Naval installations are joining others across the nation to prepare for the worst case scenario, an attack on their home base.
The Navy fleet and force is used to responding to attacks anywhere in the world. But this week they're practicing how to respond when trouble hits home.
In the mock drill, designed to feel like the real thing, one participant called for help "You need to send the police! There's some people getting killed it's in building 3300 at Naval Base San Diego!"
Excercise Solid Curtain Citadel Shield is the largest anti-terror and force protection training operation in the nation. The commanding officer called this the final exam that evaluates skills practiced all year.
The simulations change constantly to reflect changing threats to Navy installations.
It's a chance to make sure the Navy's ship and shore commands communicate well with each other and coordinate crisis response with local law enforcement.
"It's a small town within a small town," said Captain Ricky Williamson,"We operate with mutual aid agreements with the city of San Diego and National City. We lend support to each other. By doing these drills we get a chance to make sure that communication is being done properly as well. I think anybody watching this should feel safer and it should make them very proud."
This is a regular training operation that happens every year. It's not being done because there's been any specific threat made against Navy installations.