McCain stated recently "I think that people should understand that I will be Hamas's worst nightmare." So McCain is putting the full military weight of America behind behind his threat to Hamas if he becomes President.
As Glenn Greenwald points out that Hamas has a territorial dispute with Israel but what dispute do they have with America? More important, what threat is Hamas to America? When did a threat to Israel become a threat to America that requires that we become "the worst nightmare" of threats to Israel no matter what the degree of threat to America. Israel can defend themselves. That's why we give them more foreign aid than any other nation in the world.
This looks like a McCain effort to attract the American Jewish vote. It works in concert with organized the anti-Obama campaign aimed at Jews in Florida.
Go read Glenn Greenwald. See also Glenn Greenwald for a complete discussion.