U.S. counterterrorism officials said Saturday they expect additional Al Qaeda (search) bombings at lightly defended targets in Asia and Africa.

Officials speaking a day after explosions killed dozens in Morocco described strong suspicions that Al Qaeda was behind the suicide attacks in Casablanca (search), noting they resembled attacks Monday in Riyadh, Saudi Arabia's capital. This includes near-simultaneous bombings at multiple locations.

Another common thread is that both attacks involved relatively simple suicide bombings launched against "soft" targets that, unlike embassies or military bases, have limited defenses, officials said.

"We can expect more of these," said one official, who spoke on the condition of anonymity. Intelligence indicates that Al Qaeda has planned a series of bombings at targets are the world, officials have said.

But there apparently was limited information that pointed toward Morocco as a target. Recent State Department (search) travel warnings — a barometer of terrorism intelligence gathered by the CIA and other agencies — did not single out Morocco as a particular target.

In an audiotape released in February, Usama bin Laden himself described Morocco as one of several U.S. allies that was "ready for liberation."

While most recent intelligence has pointed toward attacks in Southeast Asia, the Arabian peninsula and East Africa, officials said similar strikes in Europe and the United States are also a possibility.

During the past several months, authorities have detained several people they suspect are advance scouts sent by Al Qaeda to conduct surveillance inside the United States, U.S. officials said. Their activities are still being investigated, the official said.

Officials believe last week's attacks were motivated by a desire on the part of Al Qaeda's senior leaders to demonstrate they remain a force to be reckoned with. The attacks suggest a coordinated effort across Al Qaeda to launch strikes in which a high probability of succeeding is more important than causing mass casualties.

"The horrific bombings in Saudi Arabia and Morocco remind us why this campaign will not end soon: Our foe is ruthless, resilient and hides among innocent people," CIA Director George J. Tenet (search) said during a speech at commencement ceremonies Saturday at the Georgetown University School of Foreign Service in Washington.

The organization has suffered repeated blows in 2003, including the arrest of several of its top leaders.

The move toward more traditional suicide bombings may reflect the loss of alleged Sept. 11 mastermind Khalid Shaikh Mohammed. He specialized in orchestrating high-risk, spectacular attacks like the strikes on the World Trade Center and Pentagon.

U.S. officials are also investigating whether recent Al Qaeda operations are being directed by senior leaders hiding in Iran.

Four key Al Qaeda leaders — security chief Saif al-Adil, training commander Abu Mohamed al-Masri, bin Laden's son Saad, and Abu Hafs the Mauritanian — are believed to be in Iran trying to direct operation.

The government of Iran denies sheltering any Al Qaeda figures and says they would be detained if discovered.