Portrait of a Killer: Abu Musab Zarqawi

U.S. officials today renewed their frequent pledge to capture or kill Abu Musab Zarqawi, the Jordanian-born terrorist who has survived as a master of disguise: in Western clothes, in glasses, with a beard, without a beard, or dressed in Arab garb.

"Eventually, Zarqawi will be captured or killed, that's my belief," said Larry DiRita, a Pentagon spokesman. "That's the confidence the coalition has but at the moment that hasn't happened."

U.S. officials acknowledge that yesterday's attacks in Amman are clear evidence that Zarqawi has been able to make good on his promise to export terror beyond Iraq's borders.

"I think we have to consider the possibility that Zarqawi will attack the coalition in other countries, perhaps in Europe, Australia or even the United States," said Richard Clarke, a former White House counter-terrorism advisor who is now an ABC News consultant.

Zarqawi's bold and brazen acts of terror, including personal involvement in the beheading of Western hostages and the hundreds of Iraqi bomb attacks, have catapulted him into a dominant leadership role in al Qaeda worldwide.

"He has a following now that is much, much larger than it was before the war," Clarke said.

Al Qaeda leader Osama bin Laden has effectively ceded the spotlight to Zarqawi. In an intercepted letter, bin Laden urged Zarqawi to expand his operations to Europe and beyond.

"The Zarqawi network in Europe has been used to pump volunteers into the Jihadist network in Iraq," said Alexis Debat, a former French Ministry of Defense official who is now an ABC News consultant, "and there are early signs right now these volunteers are coming back to Europe to start their own cells, and their own terrorist network; in other words, planting the seeds of the new al Qaeda."

ABC News' Maddy Sauer contributed to this report.