No the Rooskies aren't invading. UNC is testing it's emergency something-or-other system. From here (over 1 mile away) it does have the sound of a major disaster - as if a variety of fire engines, ambulances, and an air raid alert all were triggered at once.
The University's Department of Public Safety will test a newly installed UNC Emergency Alert System Siren on Wednesday, December 19 between noon and 1 p.m.
The siren will be used to sound an alarm and broadcast instructions about what to do during a life-threatening situation such as an armed and dangerous person in the area, a major chemical spill or hazard, or a tornado.
During Wednesday's test, the siren will sound for a brief period. Siren locations are at the Hinton James Residence Hall off Manning Drive; the Gary R. Tomkins Chilled Water Operations Center behind the Dogwood Parking Deck; Winston Residence Hall at the corner of Raleigh Street and South Road; and at University buildings off Airport Drive across Martin Luther King Boulevard from the Chapel Hill-Carrboro YMCA.