Roy Scheider's movie stock has really slipped in recent years, thanks to such clunkers as the sordid "52 Pickup" and the baseball/slasher flick "Night Game."

But "The Fourth War" puts him in better creative company and gives him a role that is more meaty than blustery.

Scheider stars as Col. Jack Knowles, a war hero with a chest full of ribbons and perhaps the Army's most dangerous loose cannon. He's blown every command he's been given, and all that's keeping him from being kicked out of the service is his war record and a friend at the top, Gen. Hackworth (Harry Dean Stanton). So the Army assigns him to the West German/Czech border, a place where even he can't cause trouble.

But on his first day of looking over the territory, Knowles has a fateful encounter with his Soviet counterpart on the other side of the border, Col. Valachev (Jurgen Prochnow), perhaps the only military man in the world with a shorter temper than Knowles.

Valachev and his men are on horseback, accompanied by a helicopter, chasing a Czech refugee who's racing for the border. He's not going to make it, of course, and it provides a dramatic one-on-one between Valachev and Knowles that begins with guns aimed at both sides and ends with an exchange of snow-balls.

But what appears a playful climax to a frightful confrontation is just the beginning of a series of attacks that the two men begin on one another. They aren't stupid enough — at first, anyway — to use their military might to start a full-scale war. But each is stubborn and proud enough not to want the other to outdo him. So a miniwar will suffice.

Until it begins to escalate out of control.

This is a terrific idea, and though it never approaches its potential, director John Frankenheimer takes a no-frills, let's-get-on-with-the-action approach that is quite entertaining and effective most of the way. "The Fourth War" is much less stylish than such other Frankenheimer works as "The Manchurian Candidate," "Seconds" and "Seven Days in May," but it's also miles ahead of his more recent "Dead Bang" and the aforementioned "52 Pickup." (There are even a couple of visual moments that appear to be in-jokes about a pair of Scheider's most famous films, "Jaws" and "Blue Thunder.")

On the other hand, the script, by veteran Kenneth Ross ("Black Sunday," "Day of the Jackel") and first-timer Stephen Peters, who wrote the novel on which this is based, is superficial and loaded with underdeveloped characters. (There is also a distracting and unnecessary voice-over narration by Stanton's character.)

In all, not up to the best work of any of this crew, but an entertaining action-thriller nonetheless.

"The Fourth War" is rated R for violence and profanity.