An agreement was signed between India and Switzerland to develop an intermediate-range surface-to-air missile (SAM).
Indigo was discontinued in later years without achieving full success.
Project Devil itself led to the later development of the Prithvi missile in the 1980s.
[1] The basic rocket research in the 1960s in India was done under Project Indigo.
Project Indigo was an Indo-Swiss agreement to develop intermediate-range surface-to-air missiles that was scrapped when India opted for Soviet SA-2 missiles in 1962.