Question: The Kh-15 was a missile carried by the supersonic strike bomber operated by what organization?
Context: The Raduga Kh-15 or RKV-15 (Russian: Х-15 ; NATO: AS-16 "Kickback"; GRAU:) is a Russian air-to-surface missile carried by the Tupolev Tu-22M and other bombers.  Originally a standoff nuclear weapon similar to the U.S. Air Force's AGM-69 SRAM, versions with conventional warheads have been developed. In addition to developing the C-101 and C-301 supersonic anti-ship missiles which are fairly large in size, China has developed FL-7 (FL: Fei Long, meaning Flying Dragon) supersonic anti-ship missile which can be carried on airplanes and warships.  The Feilong-7 has an effective range of 32 kilometers and a speed of Mach 1.4.  It has powerful anti-jamming capability and its supersonic flight makes terminal interception difficult.  The warhead of the FL-7 can pierce solid armor and destroy large and medium-sized surface warships.  This missile can be roughly considered as the supersonic counterpart of the subsonic C-704 anti-ship missile.  The missile is powered by a liquid fuel rocket motor and a solid rocket booster, which is under the airframe at the rear. The Venice missile launch complex was a Cold War Regulus missile firing installation "adjacent to the Venice Municipal Airport" on the Venice, Florida, beach.  Beginning in 1959, KD2U-1 drone versions of the Regulus were JATO-launched from the strip of beach in front of the airport, flew across the Gulf of Mexico for simulating a penetrating enemy bomber for test interception, and then were "recovered on the runway at Eglin" AFB.  The launch complex was one of several Eglin missile range facilities (e.g., the Anclote Missile Tracking Annex near Tampa) and conducted the "Regulus 2, KD2U intercept missile test [on] September 3, 1959" in which the "first launch of the Air Force's new Bomarc IM-99A missile [successfully intercepted] the Regulus 2 missile at 35,000 feet altitude and at supersonic speed" (the Bomarc launch complex was at tbd after "BOMARC missiles arrived Jul 1958" at Hurlburt Field.) The C-101 (FL-2) is a supersonic anti-ship missile that can be launched from air, ship, and shore.  Alternatively, the air-launched version is also called YJ-1 by Chinese, with YJ short for Ying Ji (鹰击), meaning Eagle Strike.  The missile is also known designated by Chinese as Fei Long - 2 for export (with "Fei Long" meaning Flying Dragon – 2, or FL-2 for short), and there are two side-mounted ramjet engines at the rear of the airframe.  The ship-launched version C-101 and the air-launched version YJ-1 both have integrated fire control system to meet the tight space requirement on board ships and aircraft, where the coastal defense version FL-2 has a distributed fire control system, where power, radar, and operator consoles are located separately to reduce the possible damage from enemy attacks.  This is a practice commonly adopted by other Chinese missiles such as Silkworm missiles.  The NATO reporting name for this missile is CSSC-5 Saple.  The development of C-101 missile started in the late 1970s, and production began in the mid-1990s, as part of the replacement of the obsolete HY-2/CSS-N-2 missiles.  The Chinese Navy tested the C-101 anti-ship missile on the Hoku-class missile boat, and Huang-class missile boat are being fitted with four C-101 launch tubes, while smaller classes carry two launch tubes.  The air-launched version has been reportedly carried on the H-5 and Xian H-6 bombers and the Harbin SH-5 amphibian and eventually expanded to most of the aircraft in the Chinese inventory.  The armed with a 300 kg semi-armor-piercing warhead with a delayed impact fuse.  Cruising at an altitude below 50 meters, the missile dives about 3 kilometers away from the target to 5 meters above the sea level and then dive to attack, impacting just above the waterline. The Kh-31 (Russian: Х-31 ; AS-17 'Krypton') is a Russian air-to-surface missile carried by aircraft such as the MiG-29 or Su-27.  It is capable of Mach 3.5 and was the first supersonic anti-ship missile that could be launched by tactical aircraft. The Tupolev Tu-22M (Russian: Туполев Ту-22М; NATO reporting name: Backfire) is a supersonic, variable-sweep wing, long-range strategic and maritime strike bomber developed by the Tupolev Design Bureau.  According to some sources, the bomber was believed to be designated Tu-26 at one time.  During the Cold War, the Tu-22M was operated by the Soviet Air Force (VVS) in a strategic bombing role, and by the Soviet Naval Aviation ("Aviacija Vojenno-Morskogo Flota", AVMF) in a long-range maritime anti-shipping role.  Significant numbers remain in service with the Russian Air Force, and as of 2014 more than 100 Tu-22Ms are in use. The Northrop Grumman B-21 Raider is a heavy bomber under development by Northrop Grumman.  As part of the Long Range Strike Bomber program (LRS-B), it is to be a very long-range, stealth strategic bomber for the United States Air Force capable of delivering conventional or thermonuclear weapons. The Boeing B-52 Stratofortress is a long-range, subsonic, jet-powered, strategic bomber operated by the United States Air Force (USAF) since 1955.  The B-52A first flew in 1954, and the B model entered service in 1955.  A total of 744 B-52s were built with the last, a B-52H, delivered in October 1962.  It served in the Strategic Air Command, the Air Combat Command, and the B-52H continues to serve in the Air Force Global Strike Command and the Air Force Reserve Command. The R-21 (Russian: "Р-21" ; NATO: SS-N-5 'Sark/Serb'; GRAU: 4K55) was a submarine-launched ballistic missile in service with the Soviet Union between 1963 and 1989.  It was the first Soviet nuclear missile that could be launched from a submerged submarine, and also had twice the range of earlier missiles.  It replaced the R-11FM and R-13 (SS-N-4) on many Golf and Hotel-class submarines, and was in turn superseded by the R-27 (SS-N-6 'Serb') missile carried by Yankee-class submarines. The Next-Generation Bomber (NGB; unofficially called 2018 Bomber) was a program to develop a new medium bomber for the United States Air Force.  The NGB was initially projected to enter service around 2018 as a stealthy, subsonic, medium-range, medium payload bomber to supplement and possibly—to a limited degree—replace the U.S. Air Force's aging bomber fleet (B-52 Stratofortress and B-1 Lancer).  The NGB program was superseded by the Long Range Strike Bomber (LRS-B) heavy bomber program.
Answer: Soviet Air Force