The classic answer to this question is that "math was cheap."
The Soviet Union was comparatively poor to the United States, so you create advantages where you can for the least investment. Math and national security are closely linked, aerodynamics, radio communication/RADAR, encryptions, etc. investment in rigor payed them dividends.
The Soviet Union was comparatively poor to the United States, so you create advantages where you can for the least investment. Math and national security are closely linked, aerodynamics, radio communication/RADAR, encryptions, etc. investment in rigor payed them dividends.