Replacing Richard Clarke as the nation's cybersecurity czar will be difficult, says Homeland Security Department CIO Steve Cooper. But, Cooper says in an E-mail to InformationWeek, "we will not experience any loss of focus as a result of his resignation. He built a talented team that will work in concert with the new department."

Cooper points out that Clarke, chairman of the president's Critical Infrastructure Protection Board, championed the importance of cybersecurity to America. Also, Cooper says, "his views often have been ahead of the crowd in alerting the government and the world to risks related to letting down our guard in this critical arena."

In an E-mail sent overnight on Jan. 30 to colleagues, Clarke confirmed plans to resign from the White House, and he raised an ominous warning to colleagues about the destructive effects of future attacks on the Internet. He cited damage from the Jan. 25 Slammer attack that struck hundreds of thousands of computers worldwide, slowing E-mail and Web surfing and even shutting down some banking systems. He called the attacking software "a dumb worm that was easily and cheaply made."

"More sophisticated attacks against known vulnerabilities in cyberspace could be devastating," Clarke wrote. "As long as we have vulnerabilities in cyberspace and as long as America has enemies, we are at risk of the two coming together to severely damage our great country."

The Associated Press, citing people familiar with Clarke's plans, reported his decision to resign on Jan. 24. Clarke has spent 11 years in the White House across three administrations, and he was the president's counterterrorism coordinator at the time of the Sept. 11, 2001, terror attacks.

Clarke has focused most recently on preventing disruptions to important computer networks from Internet attacks, compiling recommendations to improve security into a "National Strategy To Secure Cyberspace."