The top commander was known publicly only by his nom de guerre, Abu Sayyaf.
"It's a very treacherous and slippery slope," Rep. Adam Schiff said.
Graham said Obama was 'not leveling with the American people" about the threat.
Obama will speak from Martha's Vineyard.
The Pentagon, though, is denying reports that a rescue operation is underway.
Some members of Congress do not want to vote on using military force until after the midterms.
We need to look at the new terms and acronyms of American foreign policy.
Obama said the mission was carried out "almost flawlessly" and vowed more strikes.
Starving 40,000 is genocide by definition in 2014; not much of a difference from 1943.
A Pentagon official said ISIS would be able to "sustain its attacks" on Iraqi forces.