Russia's next generation missile defense systems which are currently under development will be based not on the ground but in the air, former chief designer of Almaz-Antei corporation Igor Ashurbeili said. "The successor missile that will replace the S-500 (expected to enter service in 2015) won't be land-based but air-based," Ashurbeili said. He explained that air-based firepower involves placing weapons on a flying platform, in other words, on a plane. "This will be an aircraft that will fly, control the field and not only track targets, but strike them," Ashurbeili said. Ashurbeili expressed his opinion that the aerospace defense firepower will within the next 20-25 years be based on scientific and technological potential, followed by the modernization of four anti-aircraft missile systems and complexes: the Morfey (short-range), the Vityaz (mid-range), the S-400 (long-range) and the S-500(missile defenses).