Israel (and the Jewish population) has been ethnically and religiously homogenized for a long time alongside relentless violent conflict defined by that ethnicity and religion.

You end up with a society founded on ethnic and religious supremacy that has only known no-holds barred warfare for generations and an attitude that atrocities are acceptable if done in the name of God's chosen people.

That society produces people who immigrate to the US and other Western countries by the millions with those values, retaining greater allegiance on that basis than nationality. When these people come to prominence they sometimes act according to that allegiance by acting in Israel's interests, hiring other Jews into positions of power, exerting influence through media, etc.

This is interpreted by some as cultural infiltration and deliberate sabotage of American values for Israel's. There is also a long, exploitative political history between the US and Israel.