The simple reason is, the U.S. War on Terror has a defined objective and success is achievable.
I am not convinced Israel can win the Israeli War on Terror with the current policies in place and I don't believe America is prepared to go down the road necessary for victory over an enemy who will only accept the destruction of Israel as a solution. I am not sure you can win such a war and I do not want Americans dying in a war that can not be won, unless it is for vital U.S. interests.
The terrorists did not declare war on Israel, and war on America... they declared war on a culture that has overborne, overwhelmed and overtaken Islam. They declared war on the West. They see Israel as an outpost of the West... a cancer on holy Arab land.
You could remove Israel from the land, give it to the Palestinians, and the threat to America would not go away. It would increase but the Arabs would see that we will not fight for what we believe. Do we believe in Israel? Yes... but not enough to fight for it. And not enough to allow Israel to fight for herself.
It's important that you see the war in its proper context. The issue isn't America, Israel, the West Bank, or Tel Aviv... The issue is Islam.
That truth isn't going to go away because you abandon the Jews to whatever fate the terrorists have in mind... and you can't justify it away by making Israel the enemy.
The Arabs claim that the only reason there is not peace in the Middle East is because Israel occupies Palestinian lands... excusing the very aggression that delivered the lands into Israel's hand... and the very acts that continue against Israel.
As long as the terrorists threaten the West, the US is threatened. Whether the threat is against Israel, France, Poland... it threatens us.
You have spent the majority of your time on this thread bashing Israel as if they were the devil incarnate. They are not. They are a people, who 60 years ago, went into Hitler's oven because no one would stand up to Hitler.
Now, they believe they are facing the same threat. They have been invaded 3 times... they loose their children to terrorists bombs... in the 1990's they tried to make peace with the Palestinians through appeasement and it got them nothing...
Now, the Road Map tells Israel that they must accept a terrorist state on their borders so that the West can appear to be "fair and balanced" to the Arabs. The West believes that when that happens, the terror will cease. Which shows that the West has no idea why the terror began in the first place.