Entertainingly awful at times, but virtually never quite convincing, "Under Siege," the three-hour NBC Sunday night movie, at 8 on Channel 4, sounds a warning to America: face the facts of the terrorist age or risk having to sit through more films like this. Woe is we.

The movie conjures yet another not-so-distant future, one in which Hal Holbrook has been elected president of the United States (things nearly as strange have happened), and the head of the FBI, Peter Strauss, is of all things a bleeding-heart liberal who worries about the civil rights of accused terrorists. In the course of the movie, this former police chief will actually take to the streets in hot-foot pursuit of a bus on which an escaping terrorist is sitting. You wouldn't expect a Third-Worlder to do anything so bourgeois as take a cab, would you?

As the film opens, a horrible suicide bombing occurs at an army base, this time not in Beirut but in Bladensburg. Indeed, "It was bigger than the Marine barracks in Beirut," says Stan Shaw as an FBI man in one of the film's rather tasteless topical references. The massacre at the Munich Olympics is similarly invoked later. All the references are designed to impose credibility on a story that resists most such attempts, perhaps because the director, Roger Young, couldn't or wouldn't give the film the tough, pseudo-documentary crackle of a good political thriller like, say, "Seven Days in May." The subject matter is sensational and incendiary, yet the film still seems padded and squishy.

One problem for viewers is determining through whose eyes we are supposed to see the story. There are no characters with whom to empathize. Strauss' FBI chief is a whiner and a bungler, and a plot to humanize him with a subplot about adopting a child with wife Victoria Tennant is completely transparent. The screenplay, by three Washington Post writers -- Bob Woodward, Christian Williams and Richard Harwood -- in addition to Alfred Sole, achieves a surly sort of conviction only in the last third, during scenes of bickering and maneuvering in the White House, where the president's men include an excessively powerful liaison (Mason Adams) and a wildly hawkish secretary of state (E.G. Marshall, demoted from the presidency he held in "Superman"). Paul Winfield plays the secretary of defense and Fritz Weaver is the director of the CIA.

How little or how much these characters are based on real political figures is not going to be a very passionately played guessing game even inside the Beltway. But the White House stuff plays more effectively than the terrorist shtick.

After the initial bombing, terrorist acts escalate. It is the bad luck of the filmmakers that, with the memory of the shuttle tragedy still vivid, their film includes a terrorist warning that "Americans will fall from the sky." Perhaps more off-putting is the fact that the airplane bombings involve a cheap fake-out regarding the welfare of the FBI director's wife. Later, there is a blatant borrow from "The Godfather," a sequence that pointlessly crosscuts from the christening of a baby in a church to acts of random violence in the streets.

The cheekiest terrorist act depicted in the film is the rocket bombing of the Capitol dome. But not to worry, the dome bombed via special effects is really the Little Rock, Ark., capitol dome. When a character earlier says, "Hard to believe this is Washington," the knowledgeable viewer is quick to agree. Obviously a TV movie budget precluded more realistic effects. That is probably just as well. Even if we overlook the fakiness of the bombing, it's hard not to chuckle at the president's response. He's sort of peeved, as if White House squirrels stole one of his golf balls. "They bombed the Capitol," he grumps. "Crying out loud, I don't like it!" The filmmakers never do manage to synthesize an impression of widespread outrage.

Others rooting around in the cast include George Grizzard as "Warren Richards," a three- or four-fisted newspaper editor who never really figures in the story until the end, a la "Three Days of the Condor"; Beatrice Straight in a ludicrous cameo as the secretary of state's wife; and, on the purely hilarious side, Lew Ayres as a Walter Cronkite figure who comes out of retirement to "cover" the army-base bombing by standing in front of the scene and reciting his autobiography. If only this were supposed to be funny.

As an excuse for inflicting their unsavory fantasy on the great American viewer, the authors include a message, voiced by good guy Strauss. He says the people in the Mideast are not like you and me. "We insist on dealing with them as if they were the same as us. We'd better wake up," Strauss says. Unfortunately, by the time he says it, it may be well past the point of waking up for many still positioned at their TV sets.

Everyone in the movie suspects the Iranians have masterminded the terrorism (apparently "Libyans" cannot be dubbed in as a last-minute update), but the culprit turns out to be "French-Algerian." He's a mean little critter named Abu Ladeen (Thaao Penghlis), who sits in an empty loft in Detroit reciting threats into a tape recorder. One of them is "I don't think the few of us can change the world, but we can make America suffer." It sounds like something that might have been said at a network story conference during the early production stages of -- you guessed it -- "Under Siege."