Two Russians and an American in orbit commemorated Wednesday the 40th anniversary of the Apollo-Soyuz mission, when a "handshake in space" brought the two Cold War rivals closer together.

The three delivered a video address to mark the 1975 event as they floated side by side in the International Space Station (ISS), a show of fellowship at a low point in US-Russian relations today.

Bilateral ties are at their lowest ebb in decades, and space remains one of the few areas of dialogue.

Astronaut Scott Kelly and cosmonauts Gennady Padalka and Mikhail Kornienko took turns hailing the historic mission, which saw two rockets blast off in the United States and Soviet Union on July 15, 1975.

Two days later they docked in space and the three Americans and two Soviets exchanged gifts and hugs in the first symbolic step away from decades of rivalry.

It was "the first real cooperation in space of -- at that time -- two irreconcilable enemies," Padalka, the current commander of the ISS, said in the video.

It can be viewed on the Russian space agency's YouTube page: https://www.youtube.com/watch?v=uqKtFAAARwY#t=162.

The meeting was "a kind of handshake in space, the beginning of an era of worldwide warming after a protracted Cold War," Padalka said.

The Apollo-Soyuz project had to overcome many technical and cultural challenges, and the five astronauts also had difficulties speaking each other's language.

Docking seemed like an impossible task due to the many differences between the two space programmes and compromises had to be made: the United States ended up using the metric system, for example.

- East meets West -

Despite the trials, there was camaraderie and even prankery in the 20 hours spent together, as Soyuz commander Alexei Leonov drew sketches of the crew and mislabelled tubes with Russian borshcht soup to say they contain vodka.

"We were in a position to open a crack in the door between east and west," Apollo commander Thomas Stafford, now 84, said in a NASA documentary published this week, adding that he considers Leonov as his brother.

"We are proud that at the height of the Cold War, the space industries of the two countries could reach good compromise solutions," said Viktor Blagov, who was the flight director in charge of the docking.

"It would be nice to remember this today -- and not just in space," he said in an interview to Gazeta.ru website published Wednesday.

Moscow and Washington have been locked in a bitter standoff over the Ukraine crisis, with some hardliners in Russia accusing the United States of striving to destroy the country.

Last week, the commandant of the US Marine Corps claimed that Russia poses the "greatest threat" to national security.

On the ISS, however, the two countries have continued to work together, something made possible by the Apollo-Soyuz teams, Kelly said.

The mission "not only brought our nations together but paved the way for the ISS and the missions yet to unfold that will take us to the stars," he said.

ma/ser

ISS

Kelly