Trust, but verify Trust, but verify Trust, but verify (; "Doveryat, no proverit") is a Russian proverb. The phrase became well known in English when used by President Ronald Reagan on multiple occasions in the context of nuclear disarmament. Suzanne Massie, an American writer, met with President Ronald Reagan many times between 1984 and 1987. She taught him the Russian proverb "Doveryai, no proveryai" (; "Trust, but verify"), advising him that "The Russians like to talk in proverbs. It would be nice of you to know a few. You are an actor – you can learn them very quickly." The proverb was adopted
US signals intelligence in the Cold War a result of espionage by a Soviet agent, William Weisband. NSA suggests this may have been the most significant loss in US intelligence history. The Viet Minh, at first, used captured French communications equipment. Under the French, no Vietnamese had been trained in cryptography, so, the initial messages were sent in the clear. On September 23, 1945, the US intercepted a message from Ho Chi Minh to Joseph Stalin, requesting aid for flood victims. This traffic immediately triggered more suspicion of Ho's relationship to Moscow, but it turned out to be one in a series of messages to world leaders.