Ahmed Ressam, the Algerian arrested last week for attempting to enter the United States from Canada with bomb-making materials, was indicted today for transporting explosives, making false statements and smuggling.

During court proceedings, Ressam, a slight and reed-thin man with dark eyes and close-cropped black hair, kept his head slightly bowed as he listened to an interpreter translate from English to Arabic.

He did not speak during the arraignment, except to acknowledge through his interpreter that he understood the charges against him. His court-appointed attorney, Tom Hillier, said Ressam, 32, would plead not guilty.

Ressam's arrest, information gathered by U.S. intelligence officials and upcoming millennium events have raised the fear that terrorists may be targeting the United States during the holiday season, prompting government warnings about potential attacks on Americans abroad, and, for the first time today, at home. The threat has led federal authorities in the past few days to step up security at border crossings and airports and at New Year's Eve gatherings, even while they urged Americans not to panic.

"We are doing everything we possibly can," President Clinton said today at a District of Columbia soup kitchen. "We are taking extraordinary efforts in the government to act based on the incident out in the Pacific Northwest."

As the Justice Department warned that terrorists could strike on U.S. soil, Clinton advised Americans to "go about their holidays and enjoy themselves and make the most of it," but at the same time "to just be aware of their circumstances, and if they see anything suspicious to report it immediately."

A federal magistrate, citing Ressam's alleged use of false identification, his residency in Canada and reservations he had made to fly from Seattle to Chicago, New York and London, ordered Ressam held without bail until his trial, scheduled for Feb. 22.

Ressam could be sentenced to 40 years in prison if convicted of the five counts in the indictment, which did not contain any conspiracy charge. Authorities are seeking associates of Ressam but have not located the person they believe tried to cross into the United States with him.

"This is not a terrorism indictment," said U.S. Attorney Katrina Pflaumer at a news conference after the hearing. "This is a straightforward case about transporting explosives, giving false statements and smuggling."

Hillier said on the courthouse steps that federal prosecutors had not made any overtures for a plea agreement, whereby Ressam hypothetically might be offered some leniency in exchange for any information he might offer about what he or others planned to do with the explosives he was charged with trying to bring into the United States.

But Pflaumer said anyone who knew about a plot could be charged for not coming forward with information about any planned attacks. Pflaumer confirmed that the federal government had not approached Ressam with any kind of plea offer.

Authorities in the United States and abroad are investigating what ties Ressam may have to militant Islamic groups. Ressam was arrested in Canada and served a brief sentence for stealing computers and cellular telephones from vehicles. Authorities are investigating whether he is linked to the Armed Islamic Group, which is alleged to have funneled proceeds from thefts in Montreal to anti-U.S. groups. Investigators also are trying to learn if there are any links between Ressam and Saudi millionaire Osama bin Laden, who is accused of being behind the bombings of U.S. embassies in Africa last year.

In Washington, Deputy Attorney General Eric H. Holder Jr. and Dale Watson, the FBI assistant director for counterterrorism, warned of the possibility of a terrorist attack on American soil as well as against Americans traveling abroad.

The State Department has issued two warnings in the last 11 days about the potential danger to Americans overseas from terrorism, but until now the Justice Department had been silent about the home front.

Referring to the Ressam case, arrests in Vermont this week of an Algerian man traveling with false documents, and arrests in Jordan and Pakistan of suspected terrorists earlier this month, Holder said, "Events like these suggest that there is a heightened risk that there may be individuals planning attacks abroad and within the United States during the holiday season, now through mid-January."

Holder urged caution, not panic. "We ask the American people to be vigilant during this period, especially in cities where large millennium or religious activities are planned."

Holder did not discourage attendance of the millennial celebration on the Mall or in New York's Times Square. He asked that at such gatherings people be "more observant about their surroundings" and "to report any suspicious things to law enforcement."

Watson said there had been no fatwas or any other specific edicts by any terrorist groups explicitly warning of attack on Americans at home.

Holder said there would be an "extensive" law enforcement presence on the Mall for the millennial events, and officials said the Times Square New Year's Eve party also would be saturated with police.

Law enforcement officials said that the Justice Department would have issued a warning about domestic terrorism even if the arrests in Vermont and Seattle had not transpired. The millennium, they said, more than any information developed from those arrests, was guiding official pronouncements yesterday.

Holder and Watson were asked repeatedly for details about the investigation of Ressam and the arrest of Bouabide Chamchi, 20, in Vermont, who was apprehended Tuesday for attempting to enter the United States with a falsified Canadian passport. They declined to comment on either investigation.

In another case, U.S. Customs officials detained an American citizen trying to board a Miami-bound plane in the Bahamas because the individual acted suspiciously and was found to be carrying wires, magnet coils and other items. A search turned up nothing suspicious.

Staff writer Lorraine Adams in Washington contributed to this report.

CAPTION: Ahmed Ressam was accused of transporting explosives, making false statements and smuggling in case at U.S.-Canadian border.