The bi-partisan commission that probed the September 11, 2001 terrorist attacks on the United States, along with key U.S. senators, says America's vast transportation system remains vulnerable to terrorist attack. In his opening remarks, North Dakota Senator Byron Dorgan took note of the sheer number of people and vessels that enter the United States and the security challenges posed by the influx.

"1.1 million people come into this country every day, 50,000 trucks and containers come in every day, 580 vessels arrive at our ports every day, 2,500 aircraft arrive in this country every day. This is a big, wide-open country and just dealing with the security of all of this is very critical," said Senator Dorgan.

President Bush's point man for transportation safety, Homeland Security Undersecretary Asa Hutchinson, told the committee that much has been achieved over the last three years and that more will be done in the future.

"We continue to make progress every day," said Mr. Hutchinson. "We are confident that we can significantly protect the transportation system by continuing to evaluate vulnerabilities, prioritize risks, and focus resources accordingly."

But that assurance did not satisfy any of the senators at the hearing, several of whom openly voiced deep frustration. Chairman John McCain of Arizona complained that little has been done to secure America's porous borders from terrorists who may enter the country illegally.

California Senator Barbara Boxer noted a recent report that air marshals are currently assigned to a tiny fraction of U.S. commercial passenger flights. Senator Dorgan asserted that it was "nuts" that air passengers are not prohibited from carrying butane lighters on board.

"The status quo is unacceptable," said Maine Senator Olympia Snowe. "Port security: we are only spending $500 million on implementing port security mandates. The Coast Guard has estimated that it will cost seven billion dollars over the next 10 years to implement those port security mandates. Unacceptable. We have got to get these things done and much more," said Senator Snowe.

The chairman of the September 11 Commission, Thomas Kean, added several observations of his own.

"Mandated vulnerability assessments of the nation's 50 largest ports are not scheduled to be completed for years. Despite recent initiatives, the vast majority of all containers enter the country unchecked and the documentation requirements are pretty easy to circumvent," he said.

Mr. Kean highlighted several recommendations from the September 11 Commission. Among them: that federal agents and not the airlines be responsible for checking passengers' names against a national "no-fly" registry of people deemed to be security threats; that airport baggage screening be enhanced and streamlined; that the capacity to identify passengers based on so-called "biometric" identification marks, including fingerprints and eye scans, be enhanced; that blast-proof containers be installed in the cargo bays of commercial airliners; and that the percentage of cargo containers being inspected at U.S. ports be dramatically increased.

Above all, the commission's vice chairman, Lee Hamilton, said the Bush administration must craft a comprehensive plan for safeguarding America's transportation system, and insist on swift implementation.

"We need a blueprint for each mode of transportation," said Mr. Hamilton. "This includes spelling out specific goals, determining what security standards and practices will be employed to achieve them. The commission believes that Congress should set a specific date for the completion of these vital plans, hold the Department of Homeland Security responsible for achieving them, and assure that the agency has the necessary resources to implement them."

Mr. Hamilton said he realized that, in the post-September 11 era, absolute safety is not possible.

"It is not just a matter of deciding which targets to protect. It is a question of deciding what is the most likely tactic that the terrorists will use. And that is educated guesswork. And you can be wrong," he said. "And being wrong could cost a lot of money and a lot of lives. I do not envy government officials who have to make these decisions, because they are really hard. But it is important that we do it."

Picking up on that theme, commission chairman Thomas Kean said it is not enough to boost security in an attempt to foil terrorists. He said the United States must also increase its ability to respond effectively if and when an attack occurs.