An online organization claiming affiliation with the Islamic State group has posted the personal information of 100 U.S. military members and instructed supporters to kill them. Most of the Americans helped carry out bombings against ISIS in Iraq, Syria and Yemen, the Islamic State Hacking Division wrote in a letter, and should be dealt with.

“Kill them in their own lands, behead them in their own homes, stab them to death as they walk their streets thinking they are safe,” the group wrote Friday. “You crusaders that fight the Islamic State, we say to you: ‘Die in your rage!’”

The hackers went on to say they had obtained the names, addresses and photos by accessing military servers, databases and emails. But representatives from the FBI and Defense Department told the New York Times such a security compromise was unlikely. Rather, the group probably compiled the contact information from social media accounts, public records and reports on ISIS. Some of the people on the list were not even involved in the overseas airstrikes.

“I can’t confirm the validity of the information, but we are looking into it,” a Defense Department spokeswoman told the New York Daily News. “The safety of our service members is always a concern.”

The Hill reported the document, called “Target: United States Military” was posted on the Polish site “We have made it easy for you by giving you addresses, all you need to do is take the final step,” the group wrote. “So what are you waiting for?”

ISIS’s Internet prowess is nothing new, and neither is its ability to lure its supporters into action. This past week, New Jersey Air Force veteran Tairod Pugh pleaded not guilty to charges he tried to join ISIS in January. His case will likely go to trial in July.