After returning from a family outing in March 1985, Col. Roland Lajoie, head of a U.S. military liaison team authorized to monitor Soviet forces in East Germany under a Cold War accord, was notified of what the Soviets said was an “accident” involving one of his intelligence officers.

Maj. Arthur D. Nicholson had been shot and killed by a Soviet sentry while on a routine, unarmed mission to inspect a tank storage building about 100 miles northwest of Berlin.

Lajoie sped to the scene near the East German city of Ludwigslust and encountered Grigori Krivosheyev, the top Soviet general in East Germany, whose forces had their own unit permitted to observe the U.S. military in West Germany.

Krivosheyev blamed the shooting on Nicholson, claiming he had ignored the sentry’s warning. (The major’s driver later testified that no warning was given.) The Soviet general went on to protest what he called a serious violation of the rules governing the observation of each country’s forces.

“At that point, I interrupted him and said, ‘General, you have killed one of my officers, and you are protesting?’” he recounted later in an investigative report.

For the U.S. commander, the shooting was the low point in a storied but largely behind-the-scenes career in which he rose to major general, became one of the Army’s leading experts on the Soviet military, managed dangerous Cold War tensions between the two countries and implemented a historic program to destroy thousands of Soviet nuclear weapons after the breakup of the U.S.S.R.

Lajoie died Oct. 28 in Manchester, N.H., of complications from heart surgery, said his daughter, Renee Lajoie Newell. He was 87.

Nicholson was regarded by the Defense Department as the last casualty of the U.S.-Soviet Cold War, which lasted from 1947 to 1991 and claimed the lives of more than 30 Americans, although it did not involve direct combat.

In another confrontation with Krivosheyev at a Soviet military office in East Germany five days after the shooting, then-Col. Lajoie, accompanied by Marine Lt. Col. Lawrence G. Kelley, asked him repeatedly whether he felt any remorse over the death.

The Soviet general emphatically responded “Nyet!” and resumed a diatribe against the U.S. government in general and Col. Lajoie in particular, according to a confidential Army report. Then, “Lajoie and Kelley cut him off in mid-sentence and walked out of the meeting,” the report said. “The insult shocked the Soviets,” Kelley recalled.

Four months later, a 5.5-ton Soviet army truck rammed into the back of a Land Rover carrying Lajoie on a mission in East Germany, sending him to the hospital with orbital bone fractures. He was convinced it was deliberate, a response to the insult delivered by walking out on the Soviet general, said his son-in-law, Keith Detwiler.

“During that era, everything was tit-for-tat,” Detwiler said. “There was a feeling of an escalation of tensions.”

In 1988, Gen. Lajoie was assigned by the Reagan administration to set up a unit to verify Soviet compliance with the Intermediate-Range Nuclear Forces Treaty, a landmark arms-reduction agreement.

Having formed and staffed the On-Site Inspection Agency (OSIA) in a matter of months, he was on hand at a formerly secret Soviet missile base in southwestern Russia as nuclear-capable SS-20 ballistic missiles were destroyed under the pact. “He considered that the high point of his career,” Newell said.

Working with Soviet generals to ease Cold War tensions and reduce the threat of nuclear war was a remarkable turnaround for an officer who, during two stints as a U.S. military attaché in Moscow, had previously watched SS-20 missiles roll through Red Square during Victory Day parades.

The OSIA, which Gen. Lajoie directed until 1991, ultimately conducted inspections at 133 sites across the Soviet Union and confirmed the destruction of 1,800 Soviet missiles. “It was a major organizational and leadership challenge,” said Detwiler, a retired Army colonel.

Roland Lajoie was born in Nashua, N.H., on Aug. 11, 1936, and was the youngest of eight children. His parents were French Canadian immigrants from Quebec, and the family spoke French at home. His father worked in a textile mill in Nashua, and his mother was a homemaker.

The future general earned a bachelor’s degree in government from the University of New Hampshire in 1958 and a master’s in history from the University of Colorado in 1971.

In addition to his daughter Renee, of Arlington, Va., survivors include his wife of 62 years, Jo Ann Sinbaldi Lajoie, of West Wilton, N.H.; two other children, Michelle Detwiler of Falls Church, Va., and Christopher Lajoie of Alexandria, Va.; a sister; and four grandchildren.

In the 1960s and early ‘70s, he served two tours in Vietnam as an intelligence officer. From 1967 to 1970, he studied Russian at military institutes in Washington and West Germany. He was posted to Moscow as an assistant Army attaché in 1973 for three years and later as Army attaché from 1981 to 1983.

From the end of that posting until 1986, then-Col. Lajoie served as chief of the U.S. Military Liaison Mission based in West Berlin and Potsdam, East Germany. One of the most secretive units in the U.S. military, the 14-man team conducted what amounted to mutually accepted espionage on East German territory, while Soviet units did the same in West Germany.

Every day, members of the U.S. mission would drive in jeeps over the Glienicke Bridge to East Berlin, the same crossing where captured American U-2 spy plane pilot Francis Gary Powers was exchanged for Soviet spy Rudolf Abel in 1962.

The Americans and similar teams from France and Britain would fan out across East Germany, hunting especially for tactical ballistic missiles that Moscow had begun to station in Eastern Europe, the New York Times reported in 1984.

Lajoie retired from the Army in 1994, then was tapped to serve as a deputy assistant secretary in the Pentagon for cooperative threat reduction under the Clinton administration.

He led the implementation of a program under the Nunn-Lugar Act to secure nuclear materials in former Soviet states following the 1991 breakup of the U.S.S.R., a program that ultimately deactivated more than 13,000 nuclear warheads and secured thousands of pounds of fissile material.

In 1998, President Bill Clinton appointed Gen. Lajoie chairman of a U.S.-Russia joint commission to search for American service members who had gone missing on the territory of the former U.S. ally during World War II. U.S. bomber crews would fly over Soviet territory en route from the Aleutian Islands to attack Japanese targets on the Kuril Islands northeast of Hokkaido.

As chairman, Gen. Lajoie led an expedition to recover the remains of seven crew members whose plane crashed on Russia’s Kamchatka Peninsula. DNA testing identified two sets of remains; the others were unidentifiable. But the commission was able to locate six of the seven families to inform them that their loves ones were confirmed dead and no longer missing.