Air Force General Gene Renuart says defense officials are working with the Federal Aviation Administration and Canadian authorities on the project. He told The Associated Press the groups are trying to determine how unmanned aircraft can be used without interfering with busy commercial air traffic routes.

The U.S. and Canada plan to use unmanned aerial vehicles along the more than 5,000-mile long northern border. The military has chosen a base in Grand Forks, North Dakota, to base the Predator drones for that mission.

Pentagon officials say the increased military presence on the northern border is in response to shrinking arctic ice, which is expanding the amount of navigable waters. That makes it easier for security threats to sail from overseas and travel over land south into the United States.