The 'Great Green Fleet' demonstration is underway as part of the 2012 Rim of the Pacific (RIMPAC) the world's largest international maritime exercise. Beginning July 17, 2012, alternative fuels, including nuclear power, will be used in an operational setting, fueling helicopters and jets from the deck of an aircraft carrier, and refueling a cruiser and two destroyers during an underway replenishment. The demonstration will also incorporate prototype energy efficient technologies designed to enhance the combat capability of Navy warships. The ability to use fuels other than petroleum is critical to the country's energy security. "We can't afford not to do this.