Mullen also warned the audience about Yemen, which appears on the index as 13th in failed states and is home to al-Qaeda in the Arabian Peninsula; that country is another focus of the White House's new counterterrorism strategy.
"The al-Qaeda federated group that in Yemen is an incredibly dangerous group that has taken full advantage of the chaos that has been in that county, and needless to say, has intensified as we sit here today," Mullen said.
"For several years, I have worried a great deal about Yemen, really as a potential next place for al-Qaeda central. And it is becoming that fairly rapidly," he said.
Mullen said he was less worried about Afghanistan (No. 7) and Iraq (No. 9).
"Obviously these are countries that have been through enormous crisis," he said. "I'm actually fairly confident over time, that Iraq will pull itself out of its place on this index. I think Afghanistan certainly inherently does not have the resources immediately available. There is a rich abundance of resources, it's going to take time to get at that. That offers possibilities down the road."
The Failed States Index's communications director, J.J. Messner, said that while the index should not be used to predict crisis, it could serve as an early warning system for policymakers to address alarming trends, such as the rising social, economic, political and military pressures on states.
"These challenges will come at us at a speed quite frankly that is accelerating," Mullen warned. "We cannot control outcomes anymore."