Reported top speed. And it was seen as shocking enough to spur the investment into new torpedo technology. https://en.wikipedia.org/wiki/Alfa-class_submarine#I

Reported top speed. And it was seen as shocking enough to spur the investment into new torpedo technology. https://en.wikipedia.org/wiki/Alfa-class_submarine#Impact https://en.wikipedia.org/wiki/Alfa-class_submarine#Impact Like most fears over high-performance Soviet hardware though, the threat turned out to be overblown compared to the actual numbers build / operational state.