Beyrle was Ambassador in Moscow during the "reset" of Russian-American relationship, which saw the signing of the New START arms control treaty, agreement on peaceful uses of nuclear energy, Russia's accession to the World Trade Organization, and liberalized visa formalities for American and Russian travelers.

From 1977 to 1979, he served as a Russian-speaking guide on several of the cultural exhibitions that traveled across the Soviet Union under a program of exchanges organized by the United States Information Agency.

During his term as ambassador, Bulgaria signed a Defense Cooperation Agreement with the United States allowing U.S. soldiers to train at Bulgarian bases (see article on Bulgarian-American relations).

He also oversaw the end of U.S. assistance to Bulgaria from the United States Agency for International Development (USAID), and made several public speeches urging the Bulgarian Government to step up its fight against organized crime and corruption.

The daily newspaper Standart commented: "for the first time he explained in fluent Bulgarian why the United States is concerned about organized crime and corruption in Bulgaria.

He gave frequent media interviews and speeches in Russian to explain America's desire for better relations, including to university audiences in Vladivostok, St. Petersburg, Nizhniy-Novgorod and Sochi.

[6] On October 29, 2010, Ambassador Beyrle celebrated the connections between American and Russian literature and culture by hosting an Enchanted Ball at Spaso House.

Although serious differences remained over missile defense, the occupation of Georgian territory and human rights, the political relationship was less confrontational than it had been in previous years.