Except for the Claymore mine that failed to pop a string of balloons, the unstoppable M48 tank that got hung up on a log crib, and the Dragon missile that dived into the dirt halfway to its target, the Maryland National Guard put on an impressive display of military firepower Saturday at Fort A.P. Hill.

Operation Thunderbolt, a live-fire joint training exercise designed to highlight the "Soviet threat" and the Maryland Air and Army National Guard's ability to neutralize it, somehow managed to bring a festive air to the grave prospect of all-out tank warfare with the Soviet Union. pleasure of watching things blow up, a skit by a mock-Soviet tank squad degenerated into a bit of East-West banter between Capt. "Vladimir Stakanov" and the 2,200 members of the Maryland National Guard who were watching the exercise from the bleachers as part of their weekend training.

Reading from a script, Capt. Stakanov, a.k.a. Russian-speaking 1st Lt. Jim Adkins, dressed in a black beret and a Red Army uniform, extolled the 4-to-1 advantage in tanks that the Soviet Union has over the United States.

"We will find your weak areas," he vowed, "breach them and advance deeply into your rear positions."

"Ooooooh." replied a chorus of guardsmen.

But the message of the day was clear. Great as the "Soviet threat" was, Maj. Gen. Warren D. Hodges, the apple-cheeked head of the Maryland Guard, promised, "We can and will win the air-land battle."

Operation Thunderbolt, the largest such exercise in four years, had as much to do with building support for the Maryland Guard as it did with global implications of Soviet military power.

The guest list of 150 included many Maryland politicians and business leaders who employ the "weekend warriors" in civilian jobs.

There were also many retired Guard members, some of whom were attracted by the chance to get a ride on a helicopter again and see old pals.

About 250 guardsmen took part in the show, which included a free-fall parachute performance, a demonstration of roped descents from airborne helicopters, and a rare view of one of the Maryland guard's two Special Forces teams.

As a squad of 10 resourceful men marched out of the woods and faced a large crowd in front of a mess hall, a captain explained that their mission was "to be able to go anywhere in the world with the purpose of bringing about a change of policy in the target country."

Members of the team, dressed in berets and backpacks and looking immune to moral qualms, introduced themselves one by one in assorted foreign languages, and then switched to English to briefly describe in expressionless tones their training and "capabilities." To ensure their effectiveness, picture-taking was not allowed until they had vanished back into their netherworld of target countries and political intrigue.

Strangely enough, a more human view of the Guard was afforded by Alan Holt's successful firing of a TOW missile. The Frederick guardsman had trained in the techniques of the TOW but never actually fired one of the wire-guided $6,000 missiles until Saturday, when his shot made him the first qualified TOW gunner in the Maryland Guard.

The crowd was hushed. The target was some orange-colored junk 2,200 yards away. The soldier before him had tried to hit a target at 800 yards with a lighter Dragori missile and had buried it in the dirt way short of the mark. Seconds passed. There was an explosion, a back-blast of dust, and a small orange ball streaked across the range at phenomenal speed, dead on. It blew up in a great mushroom of fire and black smoke, and Holt, who had guided the missile all the way, jumped up with boyish exultation, thrusting his arms in triumph to the acclaim of the bleachers.

Alas, such was not to be for the crew that hung up a tank on an obstacle of logs and dirt. Expressions of delight came from where members of the 243rd Engineering Company who constructed the barrier were sitting, but the announcer on the loudspeaker hastened to say, "This is not indicative of the crew of that tank."

The day's exercises were climaxed by a demonstration of how a squad, with help from air and backup forces, would respond to a mock Soviet tank attack.

The defenders took up positions. Two armored personnel carriers tucked themselves behind earthen ramparts and a couple of tanks rumbled into play in a cloud of dust.

Then unseen howitzers boomed in the distance and white phosphorous exploded down -- range on Range 25, a scarred dusty wasteland of demolished tanks and missile wires strewn amid goldenrod and scrub. Rockets streaked from two Cobra helicopter gunships which kept popping out of pine trees.

Missiles were launched. Machine gun and rifle fire peppered the ground, setting up a din of rimshots and snare drum rolls that sounded like drummer Buddy Rich might sound on amphetamines.

And then the antitank A-10 Thunderbolt jets came screaming out of the south, firing their 30mm nose cannons overhead and veering sharply right.

Amidst the attack Gen. Hodges beamed from his seat in the stands and afterward pronounced himself pleased with the exhibition.

"It makes you feel good," he said.