eb22: "it would make sense to be loyalty to Israel. Being disloyal to Israel can only harm the United States...."
One should be careful to distinguish between love for Eretz Yisrael as "The Land of Israel", vs "loyalty" to The Israeli Government and its various political figures.
The two are not one and the same.
It is my opinion that while "dual citizenship" is legal for Americans with regards to numerous other countries, "dual and co-equal loyalty" to two sovereign states, each with their own individual agendas and interests, is not possible.
Rabbi Kahane began one of his books with an actual reply from a well-known American Jew, who when asked the question "What would you do if one day you were to wake up and learn that America had declared War on The State of Israel?", offered this as his inane response: "If that were to happen, then I would shoot myself."
Rabbi Kahane then went on to expound on how most American Jews have refused to consider the extent of their support for, and/or loyalty to, The State of Israel, and what the ramifications would be when America would one day inevitably turn against its "ally".
If we were expected to be "loyal" to Olmert, Sharon, & Beilin, then there would be no necessity for Rabbi Meir Kahane, Chaim Ben Pesach, and JTF.
And incidentally, the United States Government has no loyalties, especially when it comes to Jews.
While it often appears that contemporary politics has the U.S.A. and the U.K. in tandem loyalty to each other, an in-depth view of our history shows that we fought not one but two wars against Britain.
Consider the historical example of West Point General Robert E. Lee from Virginia, who when learning that his beloved home state had declared War against the Union led by Washington, had to choose only one side for which to vow his loyalty and for which to fight, knowing full well that by choosing his home State of Virginia he would be forced to eventually fight his best friends and peers from West Point in deadly battle.