ISIS has urged its American sympathisers to kill 100 US military personnel whose names, addresses and photos were posted on a "death list" online.
The list was posted by the self-styled "Islamic State Hacking Division", who claimed they hacked into a number of military servers and databases to retrieve the information.
This was refuted by a US defence department official, who said the majority of the information could be found publicly, the New York Times reported.
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It appears that most of the individuals on the list are those who have been involved in bombing raids on the militant group.
The post included a message in English, which read: "We have decided to leak 100 addresses so that our brothers residing in America can deal with you.
"Kill them in their own lands, behead them in their own homes, stab them to death as they walk their streets thinking that they are safe."
The defence department could not confirm the authenticity of the information the group uploaded, but said the military was investigating.
"I can't confirm the validity of the information, but we are looking into it," a US defence official said, speaking on the condition of anonymity.
Marine Corps spokesman Lieutenant Colonel John Caldwell said: "The Naval Criminal Investigative Service is conducting in person notifications to the affected navy and marine personnel regarding this presently unverified threat/data breach."
"It is recommended Marines and family members check their online/social footprint, ensuring privacy settings are adjusted to limit the amount of available personal information," he added in a statement to the Blaze news website.
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