The Twitter feed and YouTube account for the US military command that oversees operations in the Middle East was hacked on Monday by people claiming to be sympathetic toward the Islamic State militant group being targeted in American bombing raids.
Pentagon spokesman Army Colonel Steve Warren said the Defense Department "views this as little more than a prank, or as vandalism."
"It's inconvenient, it's an annoyance but in no way is any sensitive or classified information compromised," Warren told a press briefing.
U.S. officials said the US Central Command Twitter account and its YouTube account were suspended after being compromised.
The White House said it was monitoring the extent of the hacking incident.
Two US defence officials, speaking on condition of anonymity, said the hacking was an embarrassment but that the images posted by the hackers did not appear to include classified information or pose a security threat.
"In the name of Allah, the Most Gracious, the Most Merciful, the CyberCaliphate continues its CyberJihad," the Central Command Twitter feed said after being hacked.
The Twitter feed had several messages from hackers, including one telling American soldiers to "watch your back," and the YouTube account had two videos that appeared to be linked to Islamic State.
Islamic State has taken control of parts of Syria and Iraq. The group's forces have been targeted in ongoing air strikes by the United States and international partners.
The Twitter account published a list of generals and addresses associated with them, titled "Army General Officer Public Roster (by rank) 2 January 2014."
Subsequent posts read, "Pentagon Networks Hacked! China Scenarios" and "Pentagon Networks Hacked. Korean Scenarios."
"We can confirm that the CENTCOM Twitter and YouTube accounts were compromised earlier today. We are taking appropriate measures to address the matter," Central Command said in a statement.
White House spokesman Josh Earnest said during a press briefing that the hacking was "something that we take seriously."
Earnest seemed to downplay the impact of the incident, saying, "There's a pretty significant difference between what is a large data breach and the hacking of a Twitter account."
President Barack Obama separately announced new proposals aimed at bolstering American cybersecurity in the wake of recent high-profile hacking incidents including one against Sony Pictures Entertainment that US officials have blamed on North Korea.
While it was not clear that any Pentagon network had been compromised, it did appear that the hackers were successful in temporarily gaining control of Central Command's Twitter feed, which is controlled through a password.
REVIEW OF DOCUMENTS
Reuters reviewed some of the documents released by the hackers but could not immediately identify any that appeared to contain information that compromised national security.
Some could easily be found using Google searches, including the US Department of Defenсe's "Estimated Impacts of Sequestration-Level Funding," which is available on a public government website.
Another budget document, "Program Acquisition Cost by Weapon System" is a March 2014 document available on the website of the defenсe department's comptroller. Another is a draft version of the 2015 appropriations bill for the Defence Department.
After the hacking, the heading of the Central Command Twitter account showed a figure in a black-and-white headscarf and the words "CyberCaliphate" and "I love you ISIS," using an acronym for Islamic State.
Central Command's YouTube account featured videos posted by the US military of air strikes on Islamic State targets in Syria and Iraq. It apparently was hacked to add two videos titled "Flames of War ISIS Video" and "O Soldiers of Truth Go Forth."
Central Command is based at MacDill Air Force Base in Florida and handles American military operations covering the Middle East and Central Asia. Central Command oversaw the wars in Iraq and Afghanistan and is managing the US air strikes against Islamic State in Iraq and Syria.
Islamic State has attracted followers internationally who support its hard-line Islamist message. One of the men who carried out the deadly attacks in Paris last week had declared his allegiance to Islamic State.
