Friction between the United States and Russia over Ukraine won't spell the end of the International Space Station, the head of NASA said Monday, dismissing concerns that one of the world's most prestigious scientific endeavors could fall victim to political disagreement.

The comments by NASA Administrator Charles Bolden come a week after Russia warned that it could cease cooperating with the U.S. on the project after 2020. Although Japan, Europe and Canada are also members, all currently depend on Russian Soyuz capsules to take astronauts to the space station since NASA retired its shuttle fleet.

"There is no single partner that can terminate the international space station," Bolden told reporters in Berlin, where he was attending the city's annual air show.

Bolden said that the cooperation between NASA and Roscosmos, the Russian space agency, on the International Space Station hadn't changed "one iota" in recent years. The project has withstood the increasingly frosty atmosphere between Washington and Moscow that saw the U.S. impose sanctions on Russia over its actions in Ukraine.

Still, Bolden indicated that if for one reason or other a country should drop out of the project, the others would seek to continue.

"There is no one partner that is indispensable on the International Space Station," he said. NASA hopes that private companies such as Space X will be able to develop rockets and capsules to fly astronauts to the space station as early as 2017.

Asked whether there might be an opportunity to bring on board China, which NASA is currently banned from cooperating with on human space flight, Bolden said: "There is nothing that I see in the tea leaves that says our relationship is going to change."

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NASA: Russia Alone Can't End Space Station Work