Thomas P. Stafford, an astronaut who pioneered cooperation in space when he commanded the American capsule that linked up with a Soviet spaceship in July 1975, died on Monday in Satellite Beach, Fla. He was 93.

His death, in a retirement home, was confirmed by his wife, Linda. She said he had recently been diagnosed with liver cancer.

General Stafford flew four times in space and orbited within nine miles of the moon’s surface on the mission that preceded the moon walks of Neil Armstrong and Buzz Aldrin in July 1969, fulfilling President John F. Kennedy’s quest to best the Soviet Union in the space race.

But when General Stafford flew with the civilian astronauts Donald K. Slayton, known as Deke, and Vance D. Brand in the Apollo capsule that docked with the Soviet Union’s two-man Soyuz some 140 miles above the earth, he looked beyond the rivalries of world powers.

The Cold War would linger until the collapse of the Soviet Union in 1991, but, as General Stafford suggested, the future of space lay in missions with international crews.

In 1959, when NASA chose the first group of seven astronauts for its Project Mercury in America’s race to put a man on the moon, General Stafford, a lanky, 6-foot Oklahoman who was then a junior Air Force officer, was on the selection list. He had been a test pilot and an instructor, he had graduated from a service academy, and he had a scientific bent. But he was an inch too tall for the Mercury capsules.

He enrolled at what became Harvard Business School in September 1962. But on his 32nd birthday, three days after his arrival in Cambridge, he was offered a spot in NASA’s Gemini program, since he could fit into the larger capsules that would soon be launched. He put Harvard behind him.

He flew twice for the Gemini program and became an expert in rendezvous, the linkup of two spacecraft that would be required for a moon voyage. He orbited the moon in a two-man lunar module in May 1969, scouting a landing site for Apollo 11.

Six years later, when General Stafford’s Apollo capsule caught up with the Soyuz launched by the Soviet Union, and the two spacecraft drew close in adjoining orbits, he radioed the Soviet astronauts and said, in Russian, “We have capture.” Colonel Leonov replied in English, “Well done, Tom, it was a good show.”

More than three hours later, General Stafford and Mr. Slayton crawled into the Soyuz through a connecting module while Mr. Brand remained in the Apollo to monitor its systems. General Stafford presented the Soviets with five small American flags. The Russians responded with gifts that included a sketch of the three Americans drawn by Colonel Leonov, an amateur artist.

The Soviet leader, Leonid I. Brezhnev, sent good wishes in a message transmitted by Soviet space officials, and President Gerald R. Ford spoke to the crews by telephone. Over the next 44 hours, the five spacemen took turns visiting with one another, conducting scientific experiments and holding a joint news conference before separating.

After nine days in space, the Apollo spacecraft, which had been launched from Cape Canaveral in Florida, splashed down 330 miles northwest of Hawaii, almost precisely on target. But the astronauts’ mishandling of switches during descent allowed a noxious gas to enter their chamber, affecting the lungs of all three crewmen and resulting in their brief hospitalization upon landing. Mr. Brand said he was to blame for the mishap, but General Stafford said the crew bore a collective responsibility.

That proved a footnote to a mission that thrilled Americans and Russians alike. When General Stafford and his fellow astronauts visited the Soviet Union in September 1975 as guests of their Russian counterparts, they were greeted with cheers on the streets and they signed autographs.

Thomas Patten Stafford was born on Sept. 17, 1930, in Weatherford, Okla., west of Oklahoma City. His father, Thomas Sabert Stafford, was a dentist. His mother, Mary Ellen (Patten) Stafford, had moved to Oklahoma as a child in her family’s covered wagon.

He graduated in 1952 from the United States Naval Academy where, he once told Life magazine, “I stood near the top in all the engineering subjects, and in just about everything but conduct.”

He was commissioned in the Air Force, flew fighter planes and then attended the experimental flight test school at Edwards Air Force Base in California. After graduating in 1959, he became chief of the performance branch of the aerospace research pilot school at Edwards and wrote manuals for Air Force test pilots.

General Stafford’s first spaceflight was in December 1965 when, as an Air Force major, he piloted Gemini 6, commanded by Capt. Walter M. Schirra Jr. of the Navy. Orbiting 185 miles above the earth, Gemini 6 came within a foot of the Gemini 7 capsule, carrying Cmdr. James A. Lovell Jr. of the Navy and Lt. Col. Frank Borman of the Air Force, and launched a few hours before Gemini 6 left its landing pad.

That mission marked the first rendezvous of two manned spacecraft, the kind of maneuver that had to be perfected for a lunar module to descend to the moon from a command module, which remained in orbit, and then link up with it for the trip home.

General Stafford was back in space in June 1966 as the commander of Gemini 9, flying with Capt. Eugene A. Cernan of the Navy. Initially assigned as a backup crew, they stepped in when Elliot See and Charles Bassett, the astronauts assigned to the mission, were killed in a training jet crash. Gemini 9 carried out three variations of rendezvous with a previously launched unmanned target vehicle.

On the Apollo 10 mission in May 1969, General Stafford flew in orbit around the moon with Commander Cernan in their lunar module, named Charlie Brown, while Capt. John W. Young of the Navy remained in orbit in their space capsule, Snoopy, awaiting their return. That flight scouted a potential landing site in the Sea of Tranquillity for Apollo 11 and was the first to beam live color TV images from space.

General Stafford, who received his first star in 1972, held major administrative positions in NASA after the Apollo 10 flight, then returned for his fourth space mission in the Apollo-Soyuz Test Project and was promoted to major general.

He left NASA to command the Air Force flight test center at Edwards in 1975, and in 1978 was promoted to lieutenant general and named deputy chief of staff for research and development of the Air Force. He retired in November 1979 and became an aviation consultant.

Stafford Air & Space Museum, which is affiliated with the Smithsonian, opened in his hometown, Weatherford, two years later.

General Stafford and his wife, Linda Ann (Dishman) Stafford, adopted two boys, Michael and Stas, from a Russian orphanage in 2004 with help from Colonel Leonov, who was a character witness for the couple.

In addition to his wife, Mr. Stafford is survived by Michael and Stas; his daughters, Dionne and Karin Stafford, both from his first marriage, to Faye Shoemaker, which ended in divorce; a stepdaughter, Kassie Pierce; a stepson, Mark Hill; two grandsons; four step-grandchildren; and five great-grandchildren.

While the Staffords’ boys, were adjusting to life in the United States during their first months in Oklahoma, when they were 13 and 9, General Stafford reflected on his continuing friendship with Colonel Leonov and on how the world had changed since their pioneering adventure.

“We’ve kept in close touch over the years,” he told The Oklahoman newspaper in 2004. “We talk quite a bit. He was a big Communist in the old days; now he is an investment banker.”

When Colonel Leonov died at 85 in 2019, General Stafford spoke in Russian at the funeral, held in a suburb of Moscow. He called Colonel Leonov “my colleague and friend” and said: “Alexei, we will never forget you.”

Alex Traub contributed reporting.