According to the army officials, no personal or classified data has been stolen. The army has decided to temporarily shut down the website.
One of the messages reads as, "Your commanders admit they are training the people they have sent you to die fighting."
This pro-Syrian group has been blamed for various hacking and denial of service attacks of numerous news media sites, including the Twitter account of AFP's photo service.
Army spokesman Brigadier General Malcolm Frost said in a statement, "Today an element of the Army.mil service provider's content was compromised. After this came to our attention, the Army took appropriate preventive measures to ensure there was no breach of Army data by taking down the website temporarily."
This is not the first time they have hacked website, in 2013 they created confusion in the stock market briefly by putting out a fake media tweet falsely claiming the White House was under attack.
But officials said “It was possibly the first time a US military website had been penetrated, as previous hacking had targeted Twitter accounts.”