The ads make "Under Siege" look like "Die Hard" on a battleship. It's truth in advertising.

Not content to rip off one popular thriller, however, it also veers heavily into "The Hunt for Red October" territory and then becomes "Fail-Safe."

Still, there's no question that a bigger budget and more talented supporting cast makes "Under Siege" Seagal's best film to date . . . faint praise though that may be. Too bad the filmmakers didn't pay as much attention to the script as they did to the blood-bag budget.

The expected heroic-lone-wolf-against-the-evil-pack formula runs a direct course here. Seagal is the chief cook on the nuclear battleship U.S.S. Missouri as it is being decommissioned by President Bush (with news footage integrated into the opening scenes).

It is quickly established that Seagal is a maverick with a mysterious past and that for some reason he's a favorite of the captain (Patrick O'Neal) — as if we really thought he was merely a cook.

After the president's departure, a helicopter arrives with a crew of civilians hired to throw a surprise birthday party for the captain. But, as anyone who has seen the TV commercials knows, they are actually terrorists led by ex-CIA freak Tommy Lee Jones.

Jones and friends take over the ship, arm the nuclear warheads and threaten to blow up Honolulu. It's up to you-know-who to save the day.

"Under Siege" has its share of silly subplots, chiefly a Playboy bunny (former Playmate Erika Eleniak) who comes in with the civilians to jump out of a cake . . . and remove her clothes. When Seagal rescues her, she insists on tagging along and by the end of the film is a weapons expert in her own right.

This is by-the-numbers stuff, though some location work, chiefly aerial camera shots of the Missouri, lend an air of excitement, if not necessarily authenticity.

The veteran supporting cast — Jones, O'Neal, Gary Busey, Colm Meaney, etc. — bring the acting level here considerably higher than most films of this type. It's still cartoonish but the camp value gets a jolt from Busey and Jones trying to out-crazy each other. (Jones wins, though Busey gets the biggest laugh with a line about his own sanity.)

"Under Siege" is certainly low-rent stuff compared to the real thing. Jones is not nearly as menacing as Alan Rickman was in the first "Die Hard." And Bruce Willis' crown as king of the action genre is secure, since Seagal has no acting skills to speak of. (He is good at kicking in heads, however.)

The film is rated R, of course, for considerable violence and gore, some profanity and female nudity.