A group calling itself the Islamic State Hacking Division published what it said were the names and addresses of 100 US military staff and urged Islamic State supporters to kill them, a monitoring group said on Sunday.
The allegedly hacked information about members of the air force, army and navy included photos and ranks of personnel, SITE Intelligence said.
The hacking group said it took the information from government servers, databases and emails.
The self-proclaimed hackers said the 100 military staff had targeted the Islamic State group in Iraq, Syria and Yemen, and called on sympathisers to mount attacks.
Defense Department and FBI officials told The New York Times they were aware of the threats and were investigating the website.
But a defense source told the newspaper most of the information was in fact available in public records and did not appear to have been hacked from government servers.
The United States is leading an international coalition targeting the Islamic State group in Iraq and Syria, where the Islamist militants have taken over swaths of territory.
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