B52H bomber crews at this Strategic Air Command base near the Canadian border have a new mission -- being ready to drop bombs in the Persian Gulf to protect oil supplies.

War plans call for the eight-engined bombers to strike at night at low level, either from North Dakota or from bases aboard, with Egypt's Ras Banas the prime candidate.

The idea is to be prepared to send a strong signal to the Soviet Union whenever oil supplies or other vital interests are threatened in distant places like the Persian Gulf or Africia.

Fourteen long-range B52Hs here and another 14 at nearby Grand Forks, N.D., Air Force Base have been organized into a quick-response outfit called the Strategic Projection Force, or Spif. Spif's slogan is "Anytime Anywhere." Training for Persian Gulf missions has reached the point that a full-dress exercise will be conducted soon.

"We do have the capability to launch a strike to the Persian Gulf right out of here in North Dakota," said Brig. Gen. John A. Shaud, commander of the 57th Air Division which includes the Spif B53H bombers. Spif planners said a B52H carrying a load of cnventional 500-pound or 750-pound bombs could make that trip from North Dakota to the Gulf and back with only two mid-air refuelings.

That two president -- Jimmy Carter and Ronald Reagan -- have reassigned some of the B52s formerly reserved for doomsday nuclear strikes to protecting Persian Gulf oil dramatizes how priorities have changed as the world scramble for resources heats up.

Also, the fact that Washington is once again casting strategic B52s for tactical bombing in a distant Third World nation indicates a fresh attempt to try to fine-tune U.S. military responses to world crises. Many B52s were transformed from their nuclear role in the 1960s into carriers of the iron bombs dropped on North and South Vietnam.

Gen. Curtis E. LeMay complained back then that the civilians' tit-fopr-tat use of air power in Vietnam amounted to "swatting at flies rather than hitting the manue pile." Today, however, Air Force leaders are enthusiastic about tightly controlled deployment of their B52s to make a point in a troubled area, with the Persain Gulf the focus.

Gen. Richard H. Ellis, commander of the Strategic Air Command -- a job LeMay held in the glory days of big bombers -- contends, for example, that sending B52s rather than troops to the Gulf would widen the firebreak between conventional and nuclear war.

"When you talk about Southwest Asia," Ellis said in an interview, "our chances of stopping the Soviets on the land mass are extremely limited. I think everybody understands that."

If the United States puts a Marine brigade on the ground in a place like Iran to stop the Soviets, and the Marines were about to be slaughtered by overwhelming forces, Ellis continued, U.S. leaders would come under pressure to employ nuclear weapons to save the day.

"The last thing we want to do," said the SAC commander, "is to be the one who has to initiate nuclear weapons to salvage a force. With air power you don't set yourself up on a beachhead immediately and get yourself in a position where you may have to use nuclear weapons."

Besides that, Ellis maintained, sending B52s to the trouble spot in the first hours of a crisis might be enough to freeze the Soviet military. Bombs might not have to be dropped at all, as long as the will and ability to do so were demonstrated, he argued.

The B52s would be saying "you're getting into one of our vital interests. One thing the United States and Soviet Union have not done in a long time is to challenge each other's vital interests," the four-star general said. t

Ellis conceded that B52s could get shot down in such signal-sending missions, especially if they actually entered a battle zone to drop bombs. But he predicted the American people and their leaders would tolerate such losses without demanding nuclear retaliation.

"Military aircraft have been lost before," said Ellis. "We've had them shot down before. Nobody likes it, but we accept it. We haven't had divisions or regiments isolated and placed in position where greater force must be applied or write them off. What we do with Spif is give decision-makers an option to apply force in the signal-giving mode."

Given the deadlines of Soviet anti-aircraft weapons, like radar-directed guns and smart missiles, one might assume that the Spif crews being trained by the Persian Gulf might feel like kamikaze pilots. Interviews with young Americans long accustomed to waiting around the clock for the president's doomsday orders to nuke Russia revealed relish for this additional mission. It is natural for warriors to try out what they have learned. Lusting for combat is considered "the right stuff" among aviators.

"I don't forsee us flying in the big war, the nuclear war, the EWO [emergency war order] profile," said Maj. Jerry J. Swank, 36, of Lucerne, Ind., With an air of resignation. He commands one of the 14 B52H Spif bombers here that stand ready to go to war. c

Nuclear-tipped missiles, including Minuteman ICBMs dug into the black farm land all around this base, would be the more likely doomsday response, Swank reasoned, not his B52.

"But to put out firefights somewhere in the world, or to show national will to achieve our objectives, I think that's a very relistic mission. We can get into an area very fast. In two or three days we can bombing. I can see that happening much more than our normal SAC mission."

But what about the risks of being shot down?

Lt. Neil A. Harski, 24, of Cicero, Ill., a stringy copilot with the innocent face of a clean-scrubbed farm boy, said he is confident he could hold his giant bomber in turbulent air close to the ground where enemy radar would be blinded by the clutter of images.

Similarly, Capt. Russell A. Stowe, 29, of Winslow, Ala., an electronics warfare crew member, predicted the combination of surprise and electronic spoofing would enable his B52 to fly unscathed through or around modern defenses. Other airmen expressed the same confidence as they sat in flight suits in the lounge of the tighly guarded building at the the edge of the runway here. They were on call to go to war as they spoke.

Summing up why he and fellow-crew members are more fired-up about their new Persian Gulf mission than remaining ready to strike Russia with nuclear weapons, pilot Swank said matter-of-factly: "It's more viable." w