Massie, who served as Reagan's back channel to the Soviet Union, was directed by Reagan to help facilitate a meeting with Gorbachev. He tasked her with a secret trip to Moscow to find out why the Kremlin had been ignoring his invitation to Gorbachev to visit the White House for a bilateral meeting, she said.
"I was, of course, received by KGB and big boys from GRU," Massie said, recalling her arrival to Moscow to address Gorbachev's invite.
A high-level GRU official held a secret meeting with Massie inside a noisy restaurant, she said.
"I asked the person who happened to be a very important person in GRU, who was the chief agent of GRU," Massie said. "He said he [Gorbachev] would be killed. The way he said that, I know he did not mean that we [the United States] would kill him, but somebody else would kill him. Then he said he [Gorbachev] is too important to us."
Massie said the GRU informed her during the meeting that Gorbachev would not be visiting the United States.
"So I went home and I told the President [Reagan] immediately," Massie said regarding the GRU's warning. "You know what the President said? He says, 'Yes, I know exactly.' They want to have something happen here so that they can break up the discussions that the Presidents were doing together."
Gorbachev proceeded to visit Washington in early December in 1987 to meet Reagan despite the GRU's warning, Massie said.
Massie, citing a book written by Gorbachev's translator, said the United States took extraordinary measures to protect Gorbachev during his visit to Washington.
"He [Gorbachev's translator] had never ever in any country ever seen so much precautions," Massie said. "And I knew why. I knew why. And the United States I will say did a great job. Because if you remember Gorbachev walked the streets of Washington and talked to people. We did a great job."
Gorbachev's trip to Washington was a very successful visit and Reagan was very happy, Massie said.
"It would have been terrible if he [Gorbachev] had been killed in the United States," Massie said.
Massie operated as an unofficial advisor to Reagan on the Soviet Union from 1984-1988. During her service, Massie shared with Reagan her extensive knowledge of Russian culture and people, helped him prepare for the meetings with Gorbachev and contributed to ending the Cold War between the two countries. She famously taught Reagan the Russian proverb, "trust but verify," which he repeatedly used during missile treaty talks with Gorbachev.
The last leader of the Soviet Union passed away on Tuesday at the age of 91 in Moscow after a long and serious illness. He was laid to rest at the Novodevichy cemetery in the Russian capital after a public farewell ceremony on Saturday.