"Regretfully, the Arab revolutions were able to shake the dictatorships but weren't able to fill the void in the right way," Maliki said Thursday during a speech at the U.S. Institute of Peace. "So a vacuum was created, and al-Qaida and other terrorist organizations were able to exploit it and to gain ground."
Maliki said al-Qaida benefited from "the fall of the state structure" in Syria.
"The situation in the whole Middle East gave a new chance for terrorists," he said. "Terrorists came back to Iraq when the ... conflict started in Syria."
Some U.S. military officials said al-Qaida's rise in Iraq has been fueled mainly by government miscues, adding that militants would be experiencing a resurgence even if there weren't a civil war in Syria, The Wall Street Journal reported Thursday.
U.S. military leaders agree regional instability contributed to al-Qaida's heightened strength in the Middle East, and many said they believe the civil war in Syria isn't directly driving violence in Iraq, the Journal said.
"They are connected, but they are not the same," Gen. Lloyd Austin, the top U.S. commander in the Middle East, told the newspaper. "The rise of violence came about in different ways."