[Thud]

I believe about 15-20% of Israeli Jews immigrated from Russia after the Soviet Union collapsed.

[Wallace T.]

A large portion of the Jewish emigration from the USSR to Israel occurred in the 1970s, when the Soviet system was still operational. It was part of detente. Many Soviet subjects with fractional or even no Jewish ancestry made affirmative statements that they were Jewish. In the pre-DNA testing days, there was no foolproof method to determine is someone was actually Jewish.