The Boeing F/A-18E and F/A-18F Super Hornet are a series of American supersonic twin-engine, carrier-capable, multirole fighter aircraft derived from the McDonnell Douglas F/A-18 Hornet, in service with the armed forces of the U.S., Australia, and Kuwait. The F/A-18E single-seat and F/A-18F tandem-seat variants are larger and more advanced versions of the F/A-18C and D Hornet, respectively. A strike fighter capable of air-to-air and air-to-ground/surface missions, the Super Hornet has an internal 20mm M61A2 rotary cannon and can carry air-to-air missiles, air-to-surface missiles, and a variety of other weapons. Additional fuel can be carried in up to five external fuel tanks and the aircraft can be configured as an airborne tanker by adding an external air-to-air refueling system. Although officially named "Super Hornet", it is commonly referred to as "Rhino" within the U.S. Navy.