Israel acts because the world won’t defend it 
"Why, he asked, doesn't Israel offer to give back the West Bank and Gaza? Why doesn't it just let the Palestinians have a state there? If the Palestinians turned it down, he said, then at least liberal opinion would be on Israel's side and would rally to its assistance. So I patiently explained to this kind, good man that Israel had, at Camp David in 2000, made precisely this offer and that it had been rejected out of hand by Yassir Arafat, not even used as the basis for negotiation. I told him that Israel was no longer in Gaza, having withdrawn unilaterally and taken the settlers with it. The Palestinians had greeted this movement with suicide bombs and rockets."
http://www.timesonline.co.uk/tol/comment/columnists/daniel_finkelstein/article5461544.ece
"Why, he asked, doesn't Israel offer to give back the West Bank and Gaza? Why doesn't it just let the Palestinians have a state there? If the Palestinians turned it down, he said, then at least liberal opinion would be on Israel's side and would rally to its assistance. So I patiently explained to this kind, good man that Israel had, at Camp David in 2000, made precisely this offer and that it had been rejected out of hand by Yassir Arafat, not even used as the basis for negotiation. I told him that Israel was no longer in Gaza, having withdrawn unilaterally and taken the settlers with it. The Palestinians had greeted this movement with suicide bombs and rockets."
http://www.timesonline.co.uk/tol/comment/columnists/daniel_finkelstein/article5461544.ece
