Excerpt from an article by Jeremy Sharon / Jerusalem Post
…In 2015, immigration to Israel hit a 15-year high, with some 30,000 Jews making aliya, including approximately 13,600 who came from Ukraine and Russia, both of which have witnessed dramatic increases in their aliya rates since 2013.
Large numbers of those people are not considered Jewish according to Halacha, meaning they are not born to a Jewish mother, but they nevertheless are eligible for the Law of Return, which grants Israeli citizenship to those with at least one Jewish grandparent. In the first aliya from the FSU in the 1990s, some 307,000 of the approximately 1 million people who came were not halachically Jewish.
According to Prof. Ze’ev Khanin, chief scientist of the Immigration and Absorption Ministry and senior lecturer in political studies at Bar-Ilan University, approximately half of the immigrants coming to Israel from the FSU above age 30 are not Jewish according to Halacha, and as many as 75 percent of younger immigrants are also not born to a Jewish mother.
In total, he estimates there are between 720,000 to 900,000 people in the FSU who are eligible for Israeli citizenship under the Law of Return.
Sociologists and Jewish leaders in Israel have worried for a long time that the large group of technically non-Jewish but integrated citizens originally from the FSU, could become alienated from the majority Jewish population if they feel they are treated as second-class citizens and looked down upon as non-Jews.
At a certain stage, it is feared, they could become another group advocating against the explicitly Jewish nature of the state and for stripping the country of its formal Jewish character.
Religious leaders also have pointed to the possibility of Jewish intermarriage with non-Jewish immigrants and their children as a further threat to the integrity of the country’s Jewish population.