The following is an extended quote from an interesting analysis by Daniel Gordis regarding US - Israeli relations.
"When Islamic State executes an innocent American -- befuddled Israelis
noticed -- Obama has the capacity for outrage and moral clarity. But in
Israel’s conflict, even though Hamas is sworn on Israel’s destruction
and has been killing innocent Israelis for years, the best that Obama
has been able to utter is the standard 'Israel has a right to defend
itself... (Israelis ask) "Why is Islamic State a 'cancer' while Hamas is
a legitimate partner in a Palestinian unity-government, about which
U.S. Secretary of State John Kerry said, 'We will work with it as we
need to'?... To use the language of the Talmud, they’re essentially
asking, 'Why was James Foley’s blood any redder than ours?'"
http://www.bloombergview.com/articles/2014-08-21/so-how-is-hamas-different-from-islamic-state-israel-wonders