“Alarmed about the growing threat from Islamic State, the Obama administration has dramatically stepped up warnings of potential terrorist attacks on American soil after several years of relative calm.
Behind the scenes, U.S. authorities have raised defenses at U.S. military bases, put local police forces on alert and increased surveillance at the nation’s airports, railroads, shopping malls, energy plants and other potential targets.
Driving the unease are FBI arrests of at least 30 Americans on terrorism-related charges this year in an array of ‘lone wolf’ plots, none successful, but nearly all purportedly inspired by Islamic State propaganda or appeals.”
Source: White House steps up warnings about terrorism on U.S. soil – LA Times