The Twitter account for U.S. Central Command was suspended Monday after it was hacked by ISIS sympathizers -- but no classified information was obtained and no military networks were compromised, defense officials said.
A series of unusual tweets were published with apparent warnings from ISIS, as well as links, images and Pentagon documents that reveal contact information for members of the military.
The first tweet was published at about 12:30 p.m. ET and read: "AMERICAN SOLDIERS, WE ARE COMING, WATCH YOUR BACK. ISIS."
The account's profile photo became a black-and-white image of a person wearing a Keffiyeh, or scarf, around their head.
"CyberCaliphate" and "i love you isis" were sprawled out in white letters against a black screen at the top of the Twitter page.
By about 1:10 p.m. ET, the account was suspended.
Central Command's YouTube page was also apparently hacked and contained ISIS propaganda videos depicting militant fighters.
The group also claimed to have obtained and released classified documents, though Central Command said that isn't true.
"These sites reside on commercial, non-Defense Department servers and both sites have been temporarily taken offline while we look into the incident further," Central Command said in a statement.
"CENTCOM's operational military networks were not compromised and there was no operational impact to U.S. Central Command. CENTCOM will restore service to its Twitter and YouTube accounts as quickly as possible. We are viewing this purely as a case of cybervandalism," the statement said.
"In the meantime, our initial assessment is that no classified information was posted and that none of the information came from CENTCOM's server or social media sites. Additionally, we are notifying appropriate DoD and law enforcement authorities about the potential release of personally identifiable information and will take appropriate steps to ensure any individuals potentially affected are notified as quickly as possible."
The Federal Bureau of Investigation is aiding a review of the hacks, an FBI official told CNN, adding that it is too soon to determine who is responsible.
At the White House briefing, press secretary Josh Earnest said the administration was "obviously looking into" the incident but did not have further information as of Monday afternoon.
"The fact that individuals claiming to be affiliated with ISIS took control of the U.S. military's Central Command's social media accounts today is severely disturbing," House Homeland Security Committee Chairman Michael McCaul, R-Texas, said in a statement.
"Assaults from cyber-jihadists will become more common unless the administration develops a strategy for appropriately responding to these cyberattacks -- including those like the North Korea attack against Sony," he said.