Russian President Vladimir Putin and Japanese Prime Minister Shinzo Abe on Saturday spoke to astronauts on board the ISS via a live video link from the Kremlin.
Russian astronaut Anton Shklaperov and his Japanese colleague Norishige Kanai, on board the International Space Station (ISS), appeared on a giant screen in the Kremlin after the two leaders held bilateral talks.
"We have been cooperating with Japan in space for over ten years," Putin told the astronauts, stressing Japan's "important contribution" to the functioning of the ISS.
"Allow me to express my joy to the fact that you work in such unity in space," Abe said, according to Russian interpreters.
"Our cooperation leads to important results," Japan's Kanai told the two leaders.
Shklaperov said it was "particularly pleasant" that the ISS celebrates the 20th anniversary of its founding in 2018, which has been declared the year of Japan in Russia and the year of Russia in Japan.
Both astronauts arrived on the ISS in December.
Putin and Abe held talks on Saturday, pledging to "reinforce cooperation" at a time of tension with the West.