WASHINGTON (AP) -- The head of the Pentagon's Cyber Command is cautioning that while al-Qaida is not capable of destructive computer attacks on the U.S., the terrorist organization could acquire that aptitude very quickly.

Army Gen. Keith Alexander said Monday in remarks at the American Enterprise Institute, a think tank, that he worries that al-Qaida and other hostile groups could become viable cybersecurity threats in the future.

Alexander also argued for legislative action to clarify the roles, standards and authorities of Cyber Command and other government agencies responsible for defending the nation against infectious computer viruses or other attacks on the nation's information systems. He said it is important to do this soon because as cyberspace grows more crowded, "the probability for crisis is mounting."