Americans (not just Jews) meddle in many other countries politics, and the rest of the world meddles in American politics. It probably has to do with the fact that Americans come from countries all over the world.
In all fairness, the future of American Jews is very closely tied to Israel, and vice versa. Without US support, Israel would have been wiped out in all its wars (i.e. American objections kept the Brits for delivering Palestine to the Arabs, and kept the Soviets from marching in on behalf of their Arab allies). Even today, American neutrality would probably cripple Israel. What happens in Israel, the growing crisis between the hareidim and the dati leumi, and to a lesser extent, the gap between religious and secular, have a major impact on the American Jewish community. One should note that a high percentage of Israeli citizens live in the United States, and American Jews are an significant community in Israel (especially if you including returned yordim such as Netanyahu).