Newsweek's Twitter feed hacked by supporters of IS

Newsweek's Twitter feed was the victim of a hack Tuesday by purported supporters of the Islamic State militant group.

"In the name of Allah, the Most Gracious, the Most Merciful, under the flag of the Islamic State CyberCaliphate continues its CyberJihad," a message pinned to the top of Newsweek's Twitter feed read. "While the US and its satellites are killing our brothers in Syria, Iraq and Afghanistan we are destroying your national cybersecurity system from inside."

In a series of tweets, the hackers posted what they claimed were confidential documents from the U.S. Department of Defense Cyber Crime Center, including an organizational chart, an internal phone list and a draft of a pilot project on social media analysis — though that document was labeled "unclassified."

Another tweet included a threatening message directed to first lady Michelle Obama.

"#CyberCaliphate Bloody Valentine's Day #MichelleObama!" the tweet read. "We're watching you, you girls and your husband!"

At the White House, press secretary Josh Earnest told reporters that the incident is being investigated by the FBI.

Newsweek's avatar was temporarily changed to the image of a masked militant next to the phrase "Je suIS IS."

The same group claimed responsibility for recent high-profile Twitter hacks of the U.S. Central Command (@Centcom) and the official Twitter account of Taylor Swift.

The tweets were quickly deleted, and Newsweek apologized to the magazine's 2.5 million Twitter followers.

"We can confirm that Newsweek's Twitter account was hacked this morning, and have since regained control of the account," Newsweek Managing Editor Kira Bindrim said in a statement. "We apologize to our readers for anything offensive that might have been sent from our account during that period, and are working to strengthen our newsroom security measures going forward."

Newsweek's website and Facebook page were unaffected.

The breach came shortly after Newsweek and other media outlets reported that the family of IS hostage Kayla Mueller had confirmed her death.

Newsweek Editor-in-Chief Jim Impoco referenced the hack in a tweet from his personal Twitter account.