Kerry calls Sotloff murder a 'punch to the gut'

The brutal execution of U.S. journalist Steven Sotloff by Islamic militants was a "punch to the gut," Secretary of State John KerryJohn Forbes KerryPrimary care is a home run for both sides of the aisle Mellman: Memories may be beautiful, yet… Lieberman: Senate should fulfill constitutional duty, confirm Mike Pompeo MORE said Wednesday.

"For so many who worked so long to bring Steven and the other Americans home safely, this was not how the story should've ended. It's a punch to the gut," Kerry said in a statement.

"Barbarity, sadly, isn't new to our world. Neither is evil. We've taken the fight to it before, and we're taking the fight to it today," he added.

President Obama, speaking in Estonia earlier on Wednesday, said that the U.S. would "not be intimidated" by the Islamic State in Iraq and Syria (ISIS) and said the U.S. would "degrade and destroy" the terrorist group.

Officials have not released how many Americans might still be held by ISIS fighters. The group has threatened to execute a British man if the U.S. continues its airstrikes in Iraq.

The murder of Sotloff, whose beheading by a masked militant was shown in a video uploaded Tuesday, is "an act of medieval savagery by a coward hiding behind a mask," Kerry said.

Sotloff "chronicled humanity in the face of inhumanity," Kerry said, adding that the U.S. would hold accountable those who murdered Sotloff and James Foley, another U.S. journalist who went missing in Syria last year and was seen executed in a video two weeks ago.