But the mood was gloomy in the back of the room, behind the rope lines of the press section. There, skeptical souls were trying to decide whether to put two and two together. The day before, the FBI had issued an extraordinarily sweeping warning: that there “may be additional terrorist attacks.” It had called on “all people” to immediately notify authorities of “any unusual or suspicious activity.”

Now, it seemed, the nation’s newsrooms were under siege. A third case of anthrax had turned up at a tabloid chain in Florida. (Five more were found by the weekend.) An aide to NBC News anchor Tom Brokaw had been infected, apparently from a letter with a Trenton, N.J., postmark. Someone had mailed an anthrax-carrying letter to the Reno, Nev., offices of Microsoft, a news-gathering partner with NBC. As Bush spoke, The New York Times’s city room stood empty, evacuated after a reporter had opened a suspicious, powder-filled letter with a Florida postmark. (Preliminary tests conducted later on the substance were negative.) In the East Room, reporters tried to be blase. “How come no one wants to threaten me?” asked one. But this was No Joke. “Our mailroom is down,” said another reporter. “I can’t get mail. You know what? I don’t want to.”

It just gets harder–for a jittery country, and for the president who leads it. Each new page in the textbook has more complex equations to solve, abroad and at home. Bush won early, widespread praise for his studied approach to launching war on the Taliban and Osama bin Laden. But now that the bombers and missiles have hit most of the plausible targets in Afghanistan, the question remains–what do we do next?–and the options aren’t easy. The global coalition Bush assembled remains in place, but it’s wobbly around the edges, with Pakistani leaders worried about street riots and Saudi princes worried about their credibility as guardians of Islam’s holy places.

At home, Bush faces an increasingly urgent conundrum. He has to ensure that Americans are steeled for more terrorist attacks. He must protect the economy by encouraging people to live a normal life. And he has to honor the essence of the American character, our faith in the future. Balancing normality and security here is as important, and as difficult, as rooting out the sources of terrorism overseas. “There is no rulebook for how to deal with the home front,” said a top White House official. “This is something new in 200 years.” In this war, “over there” is here. Whoever is behind the anthrax spread may have sophisticated terroristic goals in mind: not just to kill people, but to disrupt the flow of communication that defines our culture.

The president’s mastery of military and diplomatic details at a prime-time press conference–his first–wasn’t matched by a similar sure-footedness on the issue of homeland security. He didn’t seem ready for questions sure to be prompted by the FBI’s sweepingly worded alert–which had been issued four hours before his press conference. In fact, NEWSWEEK has learned, the idea sparked a furious debate inside the bureau, where officials worried it would inundate agents with flimsy, distracting leads and provoke hysteria. The White House got word of the warning at 1 p.m., but Bush’s prep sessions didn’t anticipate the obvious new question: what does the FBI mean by “unusual or suspicious activity”? The president was left to lamely joke about citizen-led crop-duster surveillance.

In Washington, there was little to laugh about. The Capitol was retrofitted with blast-resistant windows, and architects drew up plans for a tight security perimeter around the complex–until now a testament to the openness of the American political system. Officials at the Postal Service, which handles 200 billion pieces of mail per year, tried to calm the fears of its 800,000 employees, who demanded gloves and other on-the-job safeguards. Early last week White House officials called the heads of major TV networks, urging them not to broadcast the diatribes of bin Laden and his lieutenants. White House officials were calling the networks back later in the week–this time to warn anchors about the anthrax case at NBC.

As now seems familiar in the new world of terror, officials weren’t quite sure of what they knew–or didn’t know. They couldn’t find any link between the anthrax contaminations and any organized acts–let alone a link to any terrorist group, including bin Laden’s network, Al Qaeda. Nevertheless, said Vice President Dick Cheney, “we have to be suspicious.” Investigators know, he said, that bin Laden has tried to acquire biological and chemical weapons, and that terrorist manuals include instructions for their use. “Maybe it’s a coincidence,” Cheney said, “but I must say I’m a skeptic.”

If there is a terrorist connection, it would fit the pattern: attack the country at its very essence, freedom of communication. Terror hijacked a quintessentially American invention, the airplane, and in doing so slowed the pace of physical transport. Now unnamed and so far unknown forces may be attempting to hijack the mail and the media–vehicles that carry the freight of ideas and information. It’s a battle that Bush must handle with skill, but that only Americans themselves can win.