 Second, these Army teams worked closely with US Air Force Forward Air Controllers (FAC) which were enormously helpful in directing US air attacks by high-speed fighter-bombers, BARREL ROLL in northern Laos and Operation STEEL TIGER.While the FACs immediately helped, air-ground cooperation improved significantly with the use of remote geophysical MASINT sensors, although MASINT had not yet been coined as a term.The original sensors, a dim ancestor of today's technologies, started with air-delivered sensors under Operation Igloo White, such as air-delivered Acoubuoy and Spikebuoy acoustic sensors.