Twitter has fallen victim to yet another security breach, with hackers identifying themselves as member of the "Iranian Cyber Army" knocking the site offline for a brief time Thursday night.
Some of the site's features remained available during the outage, and Twitter said its API was unaffected, so people were able to send messages through third-party applications.
"As some noticed, Twitter.com was redirected for a while but API and platform applications were working," Twitter cofounder Biz Stone said in a blog post. "We will update with more information and details once we've investigated more fully."
The site is working properly now, but for a couple hours Thursday night, visitors to Twitter.com were greeted with a screen displaying a Gmail address of the group and a message expressing opposition to American control over the Internet.
The hackers' actual ties to Iran remain unclear. Twitter played a significant role in the government crackdown on demonstrators protesting the country's disputed election in June, as foreign reporters were expelled and the world read eyewitness accounts on sites like Twitter and Facebook.
At one point, State Department officials contacted Twitter executives and requested that they delay a scheduled service outage so the site would remain online in Iran.
The attack is the latest in a series of security incidents where hackers have targeted the popular microblogging service.
Earlier this year, a hacker gained access to several celebrities' accounts by posing as an administrator. That breach followed closely on an incident that saw a worm spread across the site, blasting out spam messages to thousands of users.
Twitter did not immediately respond to requests for comment for this report.
Kenneth Corbin is an associate editor at InternetNews.com. Based in Washington, D.C., Kenneth's coverage areas range from government regulation to e-commerce and online media.