Your answer from your own source
By the start of the 1980s, the
DRDL had developed competence and expertise in the fields of propulsion, navigation and manufacture of aerospace materials based on the
Soviet rocketry technologies.
After India test-fired the first Prithvi missile in 1988, and the Agni missile in 1989, the
Missile Technology Control Regime (
then an informal grouping established in 1987 by Canada, France, Germany, Italy, Japan, the United Kingdom and the United States) decided to restrict access to any technology that would help India in its missile development program. To counter the
MTCR, the IGMDP team formed a consortium of
DRDO laboratories, industries and academic institutions to build these sub-systems, components and materials. Though this slowed down the progress of the program, India successfully developed indigenously all the restricted components denied to it by the MTCR.
So,already developed countries restricted India access to tech.... from whom? OF-COURSE Russia.
IF some restrict legally,it opens another ROUTE called as ILLEGAL because buyer-India and Seller-Russian are ready to exchange.