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. The Super Hornet is in service with the armed forces of the U.S., Australia, and Kuwait. The F/A-18E single-seat and F 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. Designed and initially produced by McDonnell Douglas, the Super Hornet first flew in 1995. Low-rate production began in early 1997, reaching full-rate production in September 1997, after the merger of McDonnell Douglas and Boeing the previous month. An electronic warfare variant, the EA-18G Growler, was also developed. Although officially named "Super Hornet", it is commonly referred to as "Rhino" within the U.S. Navy. The Super Hornet entered operational service with the United States Navy in 2001, supplanting the Grumman F-14 Tomcat, which was retired in 2006; the Super Hornet has served alongside the original Hornet as well. The F/A-18E/F has been used extensively in combat operations in the Middle East, including the wars in Afghanistan and Iraq, and against the Islamic State and Assad-aligned forces in Syria. The Royal Australian Air Force (RAAF), which operated the F/A-18A as its main fighter since 1984, ordered the F/A-18F in 2007 to replace its aging General Dynamics F-111C fleet with the RAAF Super Hornets entering service in December 2010.