Production notes

The film was based on an original spec script by J. F. Lawton called Dreadnought which sold for $1 million. Warners wanted Seagal to star in the film but he turned it down at first. Seagal later said he had problems with the Jordan Tate character, "who is at first a bimbo jumping out of a cake and gets paired up with me." But he said that in revisions of the script, she "gradually reveals her intelligence."

Lawton said "We are trying to make him [Seagal] more mainstream...getting him out of the pure action genre and into an acting role." The writer added "I'm trying to bring the budget within a reasonable range. The original script was almost irresponsible, with things like battleships getting blown up...the way it was, Dreadnought would have cost $100 million-plus to make. Now we're looking at the $30 million range... It was Steven's idea to fit the Pearl Harbor Memorial into the film, because all these incredible ships would be there—a spectacular sight."

Director Andrew Davis had previously made Above the Law with Steven Seagal. Davis later said "Terry Semel wanted us to get back together again saying that Seagal was only in the movie 41 minutes. Tommy Lee is in the movie longer than Steven. It was fine, it was fine. It worked out well. We had a nice time down in Mobile and had a lot of fun making the movie, and that was the movie that got me The Fugitive so it was worth it."

In a 2018 interview with The Hollywood Reporter, Pamela Anderson claimed that she was a contender for the role of Jordan Tate, but was dropped after refusing to sleep with Seagal. Busey claimed in later interviews that Seagal sexually harassed Eleniak on set, but she has denied that Seagal ever acted inappropriately with her during casting or filming.

USS Alabama (serving as a museum in Mobile) stood in for many of the Missouri sequences, and USS Drum (museum ship) portrayed the North Korean submarine. The film also featured footage of the real Missouri sailing in Pearl Harbor, the Pacific Ocean, and San Francisco Bay. The war room sequences were filmed inside of a set constructed in a local high school gymnasium.

The film makes extensive use of the Introvision process, a variation of front projection that allows realistic three-dimensional interaction of foreground characters with projected backgrounds without the heavy cost of traditional bluescreen effects. The technique was also used in the films Outland, Megaforce, Army of Darkness and Andrew Davis' later film, The Fugitive.

"Most people are surprised that the film is as sophisticated as it is," Davis said. "It appeals to people who have a point of view about nuclear weapons and the story thrusts you into an incredible situation that is not far-fetched." When the original title Dreadnought did not test well with audiences, the marketing department wanted to give the film a three-word title like other Seagal films. They came up with Last to Surrender, which Lawton and Seagal hated. Seagal fought to have it changed, and the film ended up being called Under Siege.

Robert Booth Nichols, a self-described former espionage agent, alleged mob associate, and con artist, was employed by Seagal as a technical advisor. He also appears in the film in a small speaking role.

On its opening weekend, Under Siege made $15,760,003 from 2,042 theaters, with a $7,717 average. From there, it went on to make $83,563,139. Worldwide, it made $156,563,139. At the time, it was the most successful film that had not been screened for any critics prior to its release.

Reviewers praised Tommy Lee Jones and Gary Busey's performances as the film's villains. Rotten Tomatoes gives the film a score of 84% based on reviews from 31 critics. The site's consensus states: "A well-directed action thriller that makes the most of its confined setting, Under Siege marks a high point for early '90s action—and its star's spotty filmography." This is one of the few Steven Seagal films to receive a fresh rating on Rotten Tomatoes, along with Executive Decision and Machete, being called "Die Hard on a battleship" by film critics. On Metacritic, the film has a weighted average score of 58 out of 100 based on 17 critics, indicating "mixed or average reviews". Audiences polled by CinemaScore gave the film an average grade of "A−" on an A+ to F scale.

It was also the only Seagal movie to receive an Academy Award nomination, earning two nominations for Best Sound Effects Editing (John Leveque and Bruce Stambler) and for Best Sound (Donald O. Mitchell, Frank A. Montaño, Rick Hart and Scott D. Smith). It did not win in either category, losing to Bram Stoker's Dracula and The Last of the Mohicans. Harrison Ford saw a rough cut of the film and approved director Andrew Davis for The Fugitive (1993).

It is often considered Steven Seagal's best film to date.