by Matthew E. Berger

Jewish Telegraphic Agency

This week's coordinated terror attacks on commercial and governmental sites in New York and Washington stunned terrorism experts by their scope and sophistication -- and prompted warnings that more could be in store for American citizens.

"I was aghast at the scale and horror of this -- it is orders of magnitude beyond any other terrorist attack," said Phil Wilcox, who retired three years ago from the U.S. State Department, where he was a coordinator for counter-terrorism and an ambassador-at-large.

Both towers of the World Trade Center in New York City collapsed Tuesday when two commercial planes were hijacked and crashed into them.

Another plane crashed outside Pittsburgh, and a fourth slammed into the Pentagon outside Washington, wrecking a portion of the huge military complex.

The attacks have been called the worst against the United States since the attack on Pearl Harbor, which prompted the United States to join World War II.

Tuesday's scenario -- airplanes running into buildings -- has been discussed by U.S. counter-terrorism officials, Wilcox said. Their approach has been to tighten security at airports, since the number of plausible building targets is so vast and thus hard to monitor.

Daniel Pipes, a pundit who has written frequently on terrorism, speculated that Tuesday's attacks are only "Phase 1" of a massive assault against the United States.

"There's an incredible amount of venom in the air against the United States," said Pipes, who is director of the Middle East Forum, a conservative think tank based in Philadelphia.

Wilcox warned of the risk of copycat attacks, with this week's inauguration of a new form of terrorism.

"When there is major terrorism of this kind, it sometimes inspires others," he said. "And that's a reason for greater vigilance now."

Early media reports said a Palestinian group was behind the attacks, but that claim was later denied.

Noting the use of four aircraft as well as detailed knowledge of several U.S. airports and their security systems, Wilcox downplayed the likelihood of Palestinian-directed strikes.

"I know of no Palestinian group that has this kind of capability, organization or motivation," he said.

He pointed out that Hamas, a militant Islamic group, has never before attacked U.S. or other foreign citizens outside of its base in the West Bank and Gaza.

The secular Popular Front for the Liberation of Palestine, led by Mustafa Zibri until his death two weeks ago in an Israeli missile strike on his Ramallah office, organized airplane hijackings in years past, but had not shown itself able to pull off major terrorist attacks in recent years, Wilcox said.

"Suicide attacks have been associated with messianic religious terrorists, including Islamic terrorists," explained the former counter-terrorism official. "I use these words carefully because suicide and terror are proscribed by Islam: These are fanatic deviants."

As for a U.S. military response, Rabbi Arnold Resnicoff, who recently retired as chaplain at the Pentagon, said the military's "first actions around the scene of a terrorist attack would be, one, set up forces to guard against other attacks which might be part of the coordinated operation; two, almost simultaneously, tend to the wounded, including those who may be trapped; and three, start trying to identify those responsible, and began planning responses -- short and long term."

Suspicion has focused largely on Osama bin Laden, the Saudi billionaire who is believed to have masterminded the 1998 attacks on U.S. embassies in Africa and other terrorist incidents around the world. He is also thought to be behind Sunday's assassination, or grievous injury, of Afghan guerilla leader Ahmed Shah Massoud, the most formidable foe of the ruling Taliban movement, which has given shelter to bin Laden.

A Taliban official in Afghanistan released a statement condemning Tuesday's attacks.

While his people celebrated and distributed candy in the streets, Palestinian Authority President Yasser Arafat condemned the attacks and sent condolences to President Bush.

Bush canceled an appearance in Florida and asked for a moment of silence soon after the attacks in New York.

"I've ordered that the full resources of the federal government go to help the victims and their families, and to conduct a full-scale investigation to hunt down and to find those folks who committed this act," Bush said. "Terrorism against our nation will not stand."

The Middle East Forum's Pipes said the United States was "deeply unprepared" for this type of terrorist assault.

He argued it will be easy to determine which group is responsible for the attacks, because few have the capability. He said he hoped this would be an educational lesson for the United States, but was more cautious than some who believed it would be a turning point for U.S. counterterrorism efforts.

"If today's [attack] doesn't have a chemical or biological component, that's what we have to look for in the future," Pipes said.

Terrorism expert Steve Emerson called the series of attacks on Tuesday "unfathomable." In an 1997 article, he said he believed Muslim fundamentalist groups were preparing for a widescale attack against the United States.

"In fact, I would say that the infrastructure now exists to carry off 20 simultaneous World Trade Center-type bombings across the United States," Emerson warned in the interview with Middle East Quarterly, published by Pipes' group. "And as chemical, biological and even nuclear weapons become available to them, the threat becomes ever more ominous."

David Makovsky, senior fellow at the Washington Institute for Near East Policy, said the United States should be humble about making predictions regarding who is responsible.

"If indeed this is some sort of Islamic terrorism, the short-term impact may be giving the Israeli government more space in its fight against the threats that it faces daily," said Makovsky, former editor of The Jerusalem Post.

"There is no doubt that, at least in the short term, Americans will have a greater appreciation for what Israel has been going through on a daily basis for the last year."

JTA correspondent Sharon Samber and WJW news editor Paula Amann contributed to this report.