The 2011 TIME 100

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.

Pressure is growing on Israel to compromise, but it is difficult to imagine worse timing given the upheavals on its borders, Hamas entrenched in Gaza and Hizballah in Lebanon. Making things harder is that Bibi, 61, heads an unwieldy coalition government designed more for domestic politics than diplomacy. I've known Bibi for decades. We have clashed, and we have agreed. Like almost everyone else, I find him hard to read. He is on record supporting a demilitarized Palestinian state. But few details have been filled in. We will soon learn more. Nothing less than his legacy — and more important, the future of the Jewish state — is at stake.

Haass is the president of the Council on Foreign Relations