The US military's Central Command (CENTCOM) has said that there was "no operational impact" on military networks from a hacking incident carried out by people claiming to be working on behalf of of the Islamic State of Iraq and the Levant (ISIL).

Central Command confirmed on Monday that its Twitter and YouTube sites were compromised for about 30 minutes, but said that its "initial assessment" was that no classified information was posted by the hackers.

"Additionally, we are notifying appropriate DoD (Department of Defense) 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 command said in a statement.

Hackers had filled the CENTCOM social media site on Monday with threats that said "American soldiers, we are coming, watch your back".

"In the name of Allah, the Most Gracious, the Most Merciful, the CyberCaliphate continues its CyberJihad," the Centcom Twitter feed said after being hacked.  

Other postings appeared to list names and phone numbers of military personnel as well as PowerPoint slides and maps.

The White House said it was monitoring the extent of the hacking incident.

President Barack Obama is preparing to outline new proposals to protect the US from cybersecurity threats.

'Cybercaliphate' claim

After the hacking, the heading of the CENTCOM Twitter account showed a figure in a black-and-white headscarf and the words "CyberCaliphate" and "I love you ISIS", using another ISIL acronym.

CENTCOM's YouTube account featured videos posted by the US military of air strikes on ISIL targets in Syria and Iraq.

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It apparently was hacked to add two videos titled "Flames of War ISIS Video" and "O Soldiers of Truth Go Forth".

CENTCOM is based at MacDill Air Force Base in Florida and handles US military operations covering the Middle East and Central Asia.

It oversaw the wars in Iraq and Afghanistan and is managing the US air campaign against ISIL positions in Iraq and Syria. 

Source: Agencies