The closest U.S. ally not in NATO

[Brittain33]

invalidated by Russia-Georgia, 2008

It was invalidated when the first U.S. bombs fell on Belgrade about 10 years ago.

[Brittain33]

The U.S. got much out of its alliance with Israel the last few years according to Bush Administration policies, when our government encouraged the invasion of Lebanon and the isolation/crushing of Hamas and even discouraged Israel from ending the war in Lebanon earlier. Israel was content to be Bush's right hand in the Middle East and to be the army that the U.S. couldn't personally field against Hezbollah. Also, the bombing of the nuclear project in Syria served U.S. interests.

By and large, though, this reflects Israel's usefulness as an ally to neo-conservative foreign policy and not consistently across all U.S. interests.