(AP) -- The Twitter and YouTube sites of the military's U.S. Central Command were taken over Monday by hackers claiming to be working on behalf of the Islamic State militants. American and coalition fighters have been targeting the group with airstrikes in Iraq and Syria.

The site was filled with threats that said "American soldiers, we are coming, watch your back." Other postings appeared to list names and phone numbers of military personnel as well as PowerPoint slides and maps. The hackers titled the Twitter page "CyberCaliphate" with an underline that said "i love you isis."

Some IS militant videos were posted on the YouTube site, purporting to show military operations and explosions.

A senior defense official confirmed that the two accounts were compromised and said U.S. Central Command was taking appropriate measures to address the matter. The official spoke on condition of anonymity because the official was not authorized to speak about it publicly on the record.

The military suspended the Central Command Twitter site.