The International Press Institute (IPI) today condemned the apparent murder of freelance American photojournalist James Foley by militants seeking to carve out an Islamic state in Iraq and Syria.

A video posted online yesterday purported to depict an extremist from the Islamic State beheading Foley, who disappeared in Syria in November 2012 while reporting on the ongoing conflict in the country for the news website GlobalPost.

In the video, Foley, apparently speaking under duress, said his execution came in response to American airstrikes on the group in Iraq. A black-clad man who appeared in the video behind Foley carrying a knife also threatened another American journalist, Steven Sotloff, who disappeared in Syria in August 2013 while working for Time magazine.

In comments following Foley’s apparent murder, the man implied that Sotloff also would be killed unless the airstrikes stopped.

GlobalPost reported today that the U.S. Federal Bureau of Investigation (FBI) said that formal verification of the video remained pending, but that the FBI believed it to be authentic. Foley’s family yesterday released a statement in which they implored the kidnappers to spare the lives of other hostages and said: “We have never been prouder of our son and brother Jim. He gave his life trying to expose the world to the suffering of the Syrian people.”

GlobalPost cofounder Charles Sennott, in an interview today with WGBH’s Morning Edition, noted that facts related to the video “are very few right now”, but he remembered Foley for the journalist’s “amazing passion”.

“He was courageous, he was fearless, and at times that caused great worry, concern and anguish for his editors,” Sennott said. “Foley took risks all over — in Iraq, in Afghanistan, and definitely in Libya, where he was captured, and he was held for 45 days, and eventually released. That changed him. That changed his sense of the calculus of risk, but it didn’t change his passion for what he wanted to do.”

IPI Executive Director Alison Bethel McKenzie today commented: “We are appalled and saddened by the tragic murder of James Foley, and our thoughts and prayers go out to his family and friends, and to our colleagues and IPI family at GlobalPost. We urge the United States government, and all governments, to send a strong message to the worldwide community that attacks on journalists who are doing their jobs in conflict zones is unacceptable and will have severe repercussions.”

IPI Executive Board Vice Chair John Yearwood, who heads IPI’s North American Committee and serves as world editor for the Miami Herald, added: “I’m saddened by the horrific death of journalist James Foley, and I offer heartfelt condolences to his family and friends. James’ death underscores why IPI continues to work so hard to ensure that journalists are protected while covering stories – here in the U.S. and abroad – under often very difficult circumstances.”

*The headline on this statement was changed on Aug. 28, 2014 to reflect the general consensus that the video posted did indeed depict the murder of James Foley by an individual affiliated with the Islamic State.