Kashmiran- Well, the Americans were buddy buddy with the Israeli's during the 6 day Arab-Israeli war. They were providing all kind of air to surface intelligence to Israel. Now, in the mean time The Americans had USS Liberty ship roaming in the international waters. The ship was intercepting all kind of raw military, and strategic information from all countries involved in the war, and was sent as is to Israel. Israel was in fact losing the war before the Americans jumped in and start providing the Israeli's with military intelligence. After the American involvement in the war, the Israeli's got the upper hand and the Arab states start losing it. Finally, Syria and Jordon went to United Nations, and established a temporary seize fire with Israel. The Americans agreed with the seize fire, and told Israel not to take any military action anymore. The Israeli's wanted to take the advantage of the situation, and invade as much land as they could. Since the American were intercepting and listening all the information flying in the air with USS Liberty, the Israeli's feared that the Americans will find out about their intentions. The Israeli's decided to Attack USS Liberty, and destroy it completely. While they attacked USS Liberty, killed 37, injured 161 crew members, the Israeli army took Golan Heights.
What I will suggest, try to read about it yourself. You will have more fun

What happened