Israel a liability to the U.S.?

I'm not sure I agree with this, but it's food for a thought:

As Israel escalates its efforts to root Hamas and its rocket launchers out of Gaza, the global reaction is increasingly negative -- except in the United States. Washington provides Israel with diplomatic backing, U.N. Security Council vetoes of "anti-Zionist" resolutions, and of course $3 billion a year in military aid. But what does Israel provide in return? Yes, Israel and America cooperate on counterterrorism, but how many of the groups on which Israel provides intelligence would be gunning for the United States if it wasn't supporting Israel? Setting aside for a moment the emotional and religious anchors of the U.S.-Israel alliance, what is its value to the United States in practical, realpolitik terms?