Those groups that showed support earlier were AnonGhost, Mauritania Hacker Team, The Hackers Army,Moroccan Hackers, the Muslim Liberation Army, Ajax Team, Zcompany Hacking Crew and the Khorasan Hackers Army Team.
Mauritinia attacker also claimed of 5,000 Facebook account hacked, appeared to be taken from a 3rd party website.
Hackers new bulletin also, has been following the damages made by operation USA and reported of at least 700 websites defaced by AnonGhost.
Few days ago, the US Department of Homeland Security (DHS) believes that the campaign will mostly consist of nuisance-level attacks. And that appears to be right, since most of the websites are not from USA and are not high-profiled.
You can check the compiled paste opUSA attack, sent by M3GAFAB Security.