I know of quite a few Zionists who oppose US military aid to Israel because it gives the US government a stake in continued conflict and gives Israel less incentive to compromise. I'm quite open to the idea that ending this relationship could help bring about a more peaceful and just solution. Of course, these considerations have to be balanced against Israel's defense needs.
However, I'm not sure I agree that this is the "biggest problem." I think that the biggest problem behind the conflict - indeed, its cause - is antisemitism.
Without antisemitism, there would probably have been no Zionist movement. But at the same time, without antisemitism, we wouldn't have seen the same eliminationist rejection of the Zionist movement. I think that if the basic premise had been accepted that a Jewish homeland is as legitimate a proposition as an Arab homeland, there would either have been no conflict at all or it would've ended peacefully in a short time.