President Barack Obama is vowing that the United States ``will be relentless'' in its fight with Islamic State militants who beheaded a U.S. journalist in Iraq.

Calling for a global response to the group that now controls territory in both Iraq and Syria, Obama is condemning the group's execution of James Foley, whose death he says has left the nation heartbroken.

Speaking from Massachusetts, the president says he spoke Wednesday with Foley's family and offered condolences.

In forceful remarks, Obama said the entire world is ``appalled'' by Foley's killing. accused the Islamic State of torturing, raping and murdering thousands of people in ``cowardly acts of violence.'' Obama condemned the Islamic State group, saying it aims to commit genocide as it targets Christians and other minorities, while torturing, raping and enslaving people who are overwhelmingly Muslim.

The parents of an American journalist slain by Islamic State militants say their son died a hero for revealing the stories of oppressed people in war-torn lands.

James Foley, was abducted in 2012 and held for nearly two years. The Islamic militants posted a video showing his murder on Tuesday and said they killed him because the U.S. had launched airstrikes in northern Iraq.

Diane and John Foley addressed the media outside their Rochester, New Hampshire, home on Wednesday. It was an appearance where wrenching grief over their son's death mingled with shaking laughter over his life.

Diane Foley says her son was courageous to the end and called his death ``just evil.''

John Foley says the family is holding up but that it feels like a bad dream.

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