By Kyle Balluck - 06/29/14 03:57 PM EDT
The Islamic State in Iraq and Syria (ISIS) on Sunday declared an Islamic state, or caliphate, controlling the territory it has captured and announced that it is changing its name to the Islamic State, according to reports.
The development comes two days after President Obama downplayed national security concerns about the gains made by Sunni militants in Iraq.
ISIS spokesman Abu Mohammed al-Adnani made the announcement and proclaimed the group's chief, Abu Bakr al-Baghdadi, as caliph, The Associated Press reported.
Charles Lister, visiting fellow at the Brookings Doha Center, told Reuters that the announcement “is likely the most significant development in international jihadism since 9/11.”
"The impact of this announcement will be global as al-Qaeda affiliates and independent jihadist groups must now definitively choose to support and join the Islamic State or to oppose it," Lister added.
Obama conceded in an interview Friday on ABC that ISIS had become more powerful in “some places,” but downplayed the idea that the group's gains in Iraq meant the U.S. was in greater danger.
Speaking on CBS’s “Face the Nation” on Sunday, House Homeland Security Committee Chairman Michael McCaul (R-Texas) called ISIS the “No. 1 national security threat since 9/11.”
Iraqi troops, joined by Shiite volunteers and Sunni supporters of the government, launched an offensive against ISIS this weekend, trying to take back the key city of Tikrit.
ISIS militants seized control of Tikrit and other urban centers in northern Iraq in recent weeks.