Ray Klosowski strode into the lobby of the Natural Resources Research Institute in Hermantown. The 73-year-old wore a black leather jacket befitting the fighter pilot he’d been as an Air National Guardsman in Duluth for 33 years. He was greeted warmly by Steven Johnson.

“You can go anywhere you’d like,” said Johnson, the building manager for the facility located along U.S. Highway 53.   

“You couldn’t always do that,” Klosowski said as a way of acknowledging the building’s distant past as a secretive Cold War defense outpost - a Semi-Automatic Ground Environment (SAGE) site. The two men shared a chuckle before joining a small entourage deeper inside.

On Tuesday, Klosowski will reminisce about the significance of the facility, which once was a first-strike target for the Soviet Union, in a presentation titled, “SAGE, Duluth and the Cold War.” Klosowski’s talk begins at 10 a.m. on the building’s third floor and is open to the public.  

The facility, housing offices and laboratories of NRRI, a branch of the University of Minnesota Duluth, is different now. Built to withstand anything other than a direct hit from a nuclear warhead, the onetime SAGE building offers only a few clues to its original purpose.  

“The windows are new,” Klosowski said, indicating there were none before. New interior walls have been erected inside the 2- to 3-foot-thick exterior walls to house the NRRI’s many laboratories.

The elevators are so expansive, though, that they’re a giveaway of an underlying cargo-transporting purpose.

Klosowski explained that the elevators had to be built abnormally large in order to allow the IBM AN/FSQ-7 computers into the upper levels of the facility. The computers were the largest ever made and were at the heart of each of the country’s 22 SAGE buildings.

“Each SAGE building had two of them, 79,000 vacuum tubes each,” Klosowski said, before pointing to an iPhone. “That right there has more computer power than all 22 SAGE buildings.”

But at the time, SAGE was a security revelation that allowed the United States the ability to track a possible Soviet invasion of bomber-style aircraft. The SAGE computers required an entire floor of air conditioners to keep the massive system cool and humming. One of the powerful but temperamental computers was constantly operating while the other sat on standby.

The computers functioned in conjunction with radar lines that served as trip wires set up to span North America from east to west. A single computer featured 23 consoles, each one manned by an officer and a technician who controlled the intercepting aircraft that sat on alert at the nearby base housing the Minnesota Air National Guard’s 148th Fighter Wing, and the now--defunct U.S. Air Force 11th Fighter-Interceptor Squadron.

“We had a big Air Force base here, with 2,500 to 3,000 people,” Klosowski said. “It was a huge part of our economy. We had airmen housed downtown in the YMCA.

“People don’t realize, but Duluth was an important part of air defense in our country.”

The build-up After the surprise of Pearl Harbor drew the U.S. into World War II, the military got wise to enhancing its existing detection system for invading aircraft.  

“People in guard towers with binoculars,” Klosowski said of the old system, “which didn’t work well when it was dark or when the weather was bad.”  

The SAGE program was born in full after the Korean War. The Soviets had reverse-engineered U.S. bombers and created their own. Their nuclear program was escalating fast. American schools drilled students on what to do during a nuclear attack. Klosowski recalled a place along London Road that specialized in building bomb shelters. The wars that preceded it frayed hearts and roiled passions, but the Cold War worked best at creating anxiety. It split nerves by preying on people’s worst fears.      

On a giant antique world map that dominates a wall in one of NRRI’s offices, Klosowski pointed to a peninsula in the then-Soviet Union, just across the Bering Strait from Alaska. He pantomimed taking a string from that point into the Midwest.

“A straight line to Duluth,” he said.

To reach Chicago, Detroit or any of the Midwest’s manufacturing hubs, the Soviets would have flown directly over Duluth. As a result, the U.S. invested heavily in its air defense capabilities here, and it didn’t go unnoticed.   

“The Soviets had spies, too,” Klosowski said of Duluth’s distinction as both a strategic armament and enemy target. “Duluth went from having a sleepy little airport in 1951 to being a major air defense base.”   

In flight “I was very fortunate,” Klosowski said. “We always had the most modern airplanes. I’d have paid them to let me fly them.”

During his years of service, Klosowski rose to become a brigadier general and commanded Duluth’s 148th and then the Minnesota Air National Guard. He later directed the Duluth airport for five years. He now is on the Duluth Seaway Port Authority. But to hear him talk about life as a pilot is to hear Klosowki fondly recall some of the best times in his life.

At one point during the Cold War, he was on full-time alert for three years, meaning four to five days a week of 12-hour shifts spent poised to intercept a Soviet invasion. Two squadrons locally, totaling roughly 40 planes, were always on alert - one squadron each from the National Guard and the Air Force.

Klosowski piloted aircraft alongside teachers and other professionals who lived and worked in the community but at a moment’s notice might have had to drop everything. During air raid drills, the guardsmen would have three hours to assemble and be airborne. Failure to do so would result in a host of corrective orders. Once in the air, the pilots would work in conjunction with SAGE officers, simulating battle against real American bombers. Some of the jets could be operated remotely by the men at the SAGE consoles. All the pilot had to do was pull the trigger to fire missiles and other weaponry.

“Exercises, we called ’em,” Klosowski said. “Four to six exercises every year. We did a lot of it at night.”

Over and out The SAGE program, while innovative at the time, was relatively short-lived. Computers shrank as technology doubled and redoubled. Bombers gave way to warheads affixed atop long-range missiles, and the programs used to counteract them advanced. Ronald Reagan’s Strategic Defense Initiative, once derided as “Star Wars,” led to new technologies. But at its height, the SAGE program featured 100 squadrons on alert at points across the country.

It was an undertaking in which Klosowski was proud to play a role.  

“We had 2,400 planes dedicated to air defense,” Klosowski said. “On 9/11, we had 14 airplanes on alert in the entire U.S.”

By 1968, the 11th Fighter-Interceptor Squadron was inactivated.

“Fast rise, fast fall,” is how Klosowski described the Air Force’s history here.  

He still pays attention to what’s happening across the Bering Strait. He sees Russian President Vladimir Putin fraying nerves worldwide with a calculatedly slow invasion of Ukraine. Klosowski can’t help being reminded of the Cold War.

Americans may hope he’s not being prescient when he says, “We may get to see it again in a couple of years.”

If you go What: “SAGE, Duluth and the Cold War”

When: 10-11 a.m. Tuesday; 40-minute presentation followed by questions and the opportunity for a tour of the building

Where: NRRI building, 5013 Miller Trunk Highway (U.S. Highway 53), Hermantown