Max Boot explains:

The odds are that once Israeli troops leave, Hamas will rebuild its infrastructure, forcing the Israelis to go back in the future. This is the definition of a quagmire, yet Israel has no choice but to keep doing what it's doing. Unlike the French in Algeria or the Americans in Vietnam, it cannot simply pack its bags and go home.

And where on this scale would Americans in today's Iraq fall? Are we Israel in Gaza or France in Algeria? Or do we not really have as good an excuse as either?