Those ex-soviets are mostly jews who finally seized an opportunity to live somewhere else, outside of iron curtain. Many of them also showed up in US, see Sergey Brin.
If you are jewish it is straightforward to move to Israel, but it is a lot more complex to move to US legally. So, Israel received a lot of people from the diaspora giving them instantaneous citizenship plus economic incentives to move.
If you are jewish it is straightforward to move to Israel, but it is a lot more complex to move to US legally. So, Israel received a lot of people from the diaspora giving them instantaneous citizenship plus economic incentives to move.