Russia's President Vladimir Putin says the country's military operation in Ukraine will undoubtedly achieve its objectives.

Putin was speaking at an event to mark the country's Cosmonautics Day in its Far Eastern region of Amur on Tuesday.

Putin said Moscow had no choice but to launch the military operation to save residents in eastern Ukraine. He also said Russia has no intention of being isolated, and that it is impossible to isolate such a vast country in the modern world.

Later, Putin visited the Vostochny spaceport, now under construction, to see the launchpad for a new rocket with Belarusian President Alexander Lukashenko.

In their meeting later in the day, Putin is expected to brief Lukashenko about the Ukrainian situation, and confirm their unity to counter Western pressure.