A decree signed by Medvedev pardons Sutyagin, Alexander Zaporozhsky, Gennadi Vasilenko and Sergei Skrypal, said the spokeswoman quoted by Russian news agencies.

The four had sent a petition for mercy to Medvedev in which they pleaded guilty, she added.

The United States said earlier it would trade 10 Russian agents for four convicted Western spies after sealing Thursday a Cold War-style swap deal with Moscow to end an espionage saga neither side wanted.

A high-ranking Kremlin source said the deal had been made possible because of a “high level of trust” between the presidents of the two countries.

“This has been possible because of a new spirit in Russian-American relations, a high level of mutual understanding and the trust between the presidents of the two countries which nobody will be able to upset,” the source said.

Medvedev and US President Barack Obama, during a meeting in Washington on June 24, agreed that relaunching their countries’ relationship should be a priority.

The Kremlin source said that with his pardon Medvedev took into account that the four convicted spies had served heavy sentences.

“Sutyagin was in prison for 11 years, Zaporozhsky for nearly nine years and Skrypal for five and a half,” said the source.

During the Cold War, which ended with the fall of the Berlin Wall and the demise of communism in eastern Europe in the late 1980s and early 1990s, spy swaps between East and West often took place at Glienicke Bridge which linked West Berlin and Potsdam in what was then East Germany.