Hackers supporting Syrian President Bashar Assad's regime claimed to have broken into the website of the U.S. Army.
The official page of the U.S. Army was not accessible as of Monday afternoon, and pop-up boxes urging Washington to stop training Syrian rebels appear on a cached version of the site.
The Syrian Electronic Army (SEA), a loose hacker collective aligned with Assad, claimed responsibility for the attack on Twitter:
The extent of damages caused by the hack was not immediately clear.
The group rose to prominence following high-profile attacks on Western media organizations, including International Business Times, the New York Times and the Guardian in recent years.
In 2013 it briefly created panic on the stock market by entering the Associated Press Twitter account and posting a message saying that the White House had been attacked.
The SEA says it aims to counter what it contends is propaganda and "fabricated news" against Assad by Arab and Western media.
It has launched several spamming campaigns and DoS (denial of service) attacks on individuals and organizations hostile to the Syrian government and describes itself as a "group of enthusiastic Syrian youths who could not stay passive towards the massive distortion of facts about the recent uprising in Syria."
The group denies having financial links with the Assad regime despite continuing reports to the contrary.