The Economist‘s Lexington blog says:
Until this weekend, most people assumed that Israel enjoyed an unconditional American promise to maintain its military edge, and a nearly unconditional promise to support it in the United Nations. Now it seems that President Obama is making the continuation of some of these things conditional on Israel’s acceptance of a three-month settlement freeze, during which Israel will be pressed to agree final borders with a putative Palestinian state in the West Bank. That could be construed as a less confrontational, and more subtle, but no less effective version of the way George Bush senior forced a reluctant Yitzhak Shamir to the 1991 Madrid peace conference by withholding loan guarantees. Maybe, just maybe, the Obama peace push in Palestine has stronger legs than jaded onlookers have realised.