U.S. Air Force Senior Airman Blake Himel, left, a radio frequency transmissions systems technician with the 52nd Combat Communications Squadron, hammers a grounding wire during Vigilant Shield 15 at the Royal Canadian Air Force 5 Wing at Canadian Forces Base Goose Bay, Newfoundland and Labrador province, Canada, Oct. 18, 2014. Vigilant Shield is a weeklong annual exercise designed to emphasize an integrated Department of Defense and civil response in support of the national strategy of aerospace warning and control, defense support of civil authorities and homeland defense.