U.S. officials confirmed a cyber attack by the Syrian Electronic Army on the Marine Corps recruiting website late Monday in which the pro-Assad collective replaced the normal page with one calling on U.S. servicemen to refuse orders to fight in Syria should they be called.

The confirmation, which came in a confidential bulletin sent to U.S. officials across the country obtained by ABC News, said that the website defacement included pictures of people wearing U.S. military uniforms holding signs in front of their faces with short declarations like "I didn't join the Marine Corps to Fight for al Qaeda in a Syrian civil war."

"Obama is a traitor who wants to put your lives in danger to rescue al Qaeda insurgents," a message from the SEA on the site said, calling the Marines their "brothers."

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The Marines Corps recruiting website appears to be functioning normally as of this report, but can now be counted among the SEA's high-profile victims of cyber vandalism. Previously, the group took responsibility for disrupting service for The New York Times website, The Washington Post website, as well as taking over the Twitter accounts of The Associated Press and the satirical news website The Onion, among many others.

In the complex conflict in Syria, the U.S. government has voiced its support for the opposition, even though a major player in the rebellion is Jabhat al-Nusra, a Sunni Muslim extremist organization that has sworn its allegiance to al Qaeda.

Following an alleged chemical attack by the Syrian regime that killed hundreds, President Obama announced late last week he would seek Congressional approval before launching a military strike against the Syrian government. The President said he would not be seeking action that included American military boots on the ground.

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In an email interview with ABC News last week, an alleged leader of the SEA, who goes by the name SEA The Shadow online, said the group had been attacking the websites for major Western media outlets because the SEA believed they were spreading opposition lies about the Syrian conflict.

When President Obama was weighing a possible military strike on Syria, SEA The Shadow said that should the U.S. attack, "All American sites will be our targets and we may be more destructive."

READ: Interview With Alleged Member of the Syrian Electronic Army

Cyber security experts told ABC News last week that the SEA has shown technical and planning capabilities beyond that of the average hacktivist, but doubted the group had the skill to inflict serious damage to the U.S. military, economy or homeland infrastructure.

Still, as a U.S. official said, the group is fully on the U.S. government's radar and is considered " more than just a nuisance."

SEA The Shadow did not immediately respond to emailed requests for comment on the Marine website hack.