changed there at the navy yard since 2013? reporter: really about u.s. installations across the country. this was imposed in the middle of may. so even before the higher alert as we approach the july 4th holiday and that s what they call describing earlier threat level bravo. and then there s delta. delta means there s an attack underway. i m not aware they ve called den eded delta for the navy yard right now. but many of the things they re doing fall under that. and that is shelter in place.