Iran recently reported that it was refurbishing and returning to service its 27 elderly Russian Su-24 bombers. International sanctions prevent Russia from doing this work for them or officially helping out. Many (24) of these Su-24s were obtained when Iraq flew the bulk of its warplanes to Iran to avoid seeing them destroyed by American air attacks in 1991. Another 30 were bought from Russia in the 1980s (and five lost in the war with Iraq). Iran has struggled to maintain the all of these Su-24s but after 1991 international arms sanctions cut off maintenance support (especially spare parts) from Russia. Thus by 2002 out of the 40 Su-24s Iran had at that point, only nine were flyable. Now there are 27 Su-24s considered repairable. Iran says it has worked out a program that, using Iranian designed and manufactured components and 35,000 man hours of effort by Iranian experts and technicians per aircraft will return the Su-24s to service. So far only two of the Su-24s have completed the refurbishment process and flown. Iran reports that this all worked out as planned and the two refurbished Su-24s are back in service. But this refurbishment program has been going on for two decades and people with knowledge of it who have left Iran report that the work is often sloppy and those in charge are mainly concerned with getting the aircraft flyable, and not much else. The refurbs apparently do not last long.
While most nations using Su-24s have retired them in the last decade because they could not afford to operate and maintain them Russia is both refurbishing some of its remaining Su-24s while slowly replacing the Su-24 with the new Su-34. During the Cold War the Su-24 was the Russian answer to the American F-111 and European Tornado fighter-bombers. Introduced in the mid-1970s, it was a 43 ton swing-wing design with a crew of two and a short range (only about 600 kilometers). The original Su-24 carried eight tons of bombs and had good fire control and electronics for the time. Some 1,400 were built before production was halted in 1993. Since then most Su-24s have been retired because of old age and lack of upgrade options. Since 2000, Russia has lost sixteen Su-24s to accidents. Many more have been retired because of this tendency to become very dangerous to operate as they age. This is one of the reasons Russia is hustling to replace the Su-24s with Su-34s.
In 2008, Russia began building the first Su-34 fighter-bombers. The 45 ton Su-34 is yet another variant of the thirty-three ton Su-27 and is very similar to the thirty-six ton U.S. F-15E (a two seat fighter bomber version of the 31 ton F-15C). But Russia still has over 300 Su-24s in service and only about fifty Su-34s. It appears that the new Su-34s will not arrive quickly enough to replace most of the elderly Su-24s.
The Su-34 has a full set of defensive and offensive sensors (radars, targeting cameras, laser designators) and electronic warfare gear, it also can carry eight tons of missiles and smart bombs. Russia is currently buying fifty-eight Su-34s to replace three-hundred older Su-24s. Russia built the first twenty-four Su-34s at a cost of $36 million each (less than half the cost of an F-15E). Meanwhile, some of the more recently built Su-24s were upgraded as the Su-24M2 standard. Most of the Su-24s built are over twenty-five years old and many have been grounded several times recently because of age related problems. The Su-34 has been in the works for several years and earlier versions of two-seat Su-27 bombers were known as the Su-32.