Nobody calls Benjamin Netanyahu Benjamin. Now in his second stint as Israel's Prime Minister, he is Bibi; as with Bono, a single name suffices. His challenges, likewise, are singular. Israel is an economic success; its citizens feel relatively safe behind a security wall. But it is increasingly isolated. Most of the world views Israel as the principal obstacle to Middle East peace. Momentum is mounting in the U.N. to declare a Palestinian state this fall. Many Israelis fear the terms and consequences.