The Russian space agency rejected claims that the three cosmonauts boarded the International Space Station in the colors of the Ukrainian flag to express opposition to the invasion of Ukraine.
The three men are the first arrivals since Russia invaded its eastern neighbor last month.
Colleagues from the American, Russian and German crew welcomed them warmly, with hugs and handshakes.
The International Space Station is a project between Russia, the United States of America, Canada, Japan and several European countries.
It is led by representatives of the American-Russian partnership, which continues even after two decades despite the changing relations between the two world powers.
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Russian cosmonauts Denis Matveyev, Oleg Artemyev and Sergey Korsakov boarded the International Space Station three hours after a three-hour flight, launched from a Russian facility in Kazakhstan.
"Congratulations on a successful flight," came a voice from the Russian control center.
A few hours later, a hatch in the station opened and three smiling men rushed in, one by one in bright yellow spacesuits with blue detailing.
Standard Russian uniforms are blue, and before liftoff at least one of the cosmonauts was seen wearing it.
The moment of entry was broadcast live by both NASA and Roskosmos, the American and Russian space agencies.
"It's our time to choose colors," Artemyev said when asked about the uniforms at a live press conference.
"We accumulated a lot of yellow material, so we had to use it.
"That's why we wear yellow," joked the cosmonaut.
Since the invasion of Ukraine began, people around the world have been using the colors of the national flag to show solidarity and support.
"Sometimes yellow is simply yellow," said the press service of the Russian agency Roskosmos.
"The new crew uniforms were made in the colors of the Bauman Moscow State Technical University emblem, which all three cosmonauts completed... It's crazy to see the Ukrainian flag everywhere and in everything," the statement said.
Three Russians will begin a mission on the International Space Station that will last a little over six months.
They will replace the three current crew members who are scheduled to return to Earth on March 30.
Analysis by Jonathan AmosDdescriptors from the field of science
The colors on the uniforms certainly speak of this moment, but what is the real motivation for wearing them? Does it signal support for Ukraine or the opposite? After all, the uniforms have Russian flags on them.
Perhaps neither statement is true.
The colors are believed to be a reflection of the fact that all three cosmonauts attended Bauman State Technical University in Moscow, which has a similar color scheme.
"It's the team from Bauman," say the university.
The cosmonauts themselves, however, did not say much.
What we do know is that 400 kilometers from Earth, East and West have no choice but to continue friendly relations.
While elsewhere space cooperation is falling apart - the EcoMars rover, for example - on the International Space Station the partners are sticking together.
Russia provides propulsion for the station, Americans provide electricity - the International Space Station cannot exist without either side.
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