A horrible thing called the Holocaust happened, and we supported finding a permanent home for the survivors and their descendants. As with most nations on the earth (see Africa), the political lines were drawn according to an outsider's prefereces, and this does usually beget problems. However, I don't think berating the US for following histrical precedent is necessary.
Yes, we could have given them a nice plot of safe land in Arizona, but it was decided that they ought to be close to their holiest sites. Now they're surrounded by over a dozen theocratic and military dictatorships who are all dedicated to their destruction. I'd say we have a moral obligation to prevent that from happening.
As for who has the 'real' rights to the area... I'd say the the Israelis have done a decent job of keeping that land with the significant amount of appreciable military victories, which is also how the rest of the world does it. The Palestinians have been kicked out by superior military might. It happens. They have my sympathy for that, as do the American Indians, but I'm not going to advocate that we turn back the hands of time on either score.
Regardless, the US did not unilaterally set up Israel. The British had political control of the region at the time.
Radical muslims want to take over the world for Islam, and that goal will not stop, Israel, or no Israel.
Why did the Arabs attack Israel as soon as the UN recognized Israel as a nation?
Have you given your land back to the American Indians, yet?
The British owned it and it was filled with Jewish residents. That is hardly "arab land."
The Zionists did not all move in after 1948, they were there to begin with, many for forty or fifty years.
The Zionists were attacked immediately after Israel was declared a state--they did not have time to move masses of "settlers" in at that point.
Anyway, we supported the Arabs and the Jews sharing the land of Israel, the Arabs demanded it all and then called for the extermination of the Jews there. They're angry because they're angry. That's just how they are, they've got a barbaric culture--Just look at the Iran-Iraq War.
The Arabist apologists blame America for the Iran-Iraq War because we gave weapons to both sides--but if Saddam claimed he trusted the United States even for a second he'd be laughed out of an Arab League meeting.