The US Central Command's (Centcom) social media accounts have been hacked by a group pledging allegiance to Islamic State (IS).
Centcom confirmed in a statement that its Twitter and YouTube sites that reside on commercial, non-Defense Department (DoD) servers were compromised for nearly 30 minutes and were temporarily taken offline.
Centcom said: "Centcom's operational military networks were not compromised and there was no operational impact to Centcom. We are viewing this purely as a case of cybervandalism.
"In the meantime, our initial assessment is that no classified information was posted and that none of the information posted came from Centcom's server or social media sites."
According to media reports, the hackers posted tweets and military documents that listed contact information for dozens of current and retired senior US military personnel, as well as some PowerPoint slides showing presentations on North Korean nuclear defences and China's coastal missile defences.
In addition, two IS propaganda videos titled 'Flames of War' and 'O Soldiers of Truth Go Forth' were uploaded to Centcom's YouTube channel.
Centcom added: "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."
US military officials downplayed the incident, saying much of the information was openly available online.
Headquartered at MacDill Air Force Base in Florida, US, Centcom manages US military operations in the Middle East, North Africa, and Central Asia, and is currently overseeing the US and coalition air campaign against IS in Iraq and Syria.