The Kremlin did not specify how Goar Vartanyan (pronounced go-AR var-tahn-YAHN) might have altered the course of history. Nor did it provide any details regarding her accomplishments.

What is clear is that she and her husband were highly decorated Soviet agents who worked on numerous secret missions for 30 years in Europe, Asia and the United States. Ms. Vartanyan, whose code name was Anita, was still involved in active intelligence work when she died, the S.V.R. said.

She had a friendly relationship with the Russian president, Vladimir V. Putin. He regarded her as someone who had heroically served the Soviet intelligence service from which he later sprang, and they visited each other occasionally.

She never revealed what they discussed and always remained mum about what exactly she did.

“I helped my husband a lot at work,” is all she said in a 2015 interview with RIA Novosti, the official news agency of the Russian government. “I participated in secret operations. Together we shared failures and joys.”

Among their missions was protecting the “Big Three” Allied leaders — the British prime minister, Winston Churchill; the Soviet premier, Joseph Stalin, and President Franklin D. Roosevelt — at their 1943 strategy summit in Tehran, where they discussed the timing for opening up a second front in the war against Germany.