MOSCOW  - President Vladimir Putin was sworn in for a new six-year term on Tuesday at a Kremlin ceremony that was boycotted by the United States and a number of other Western countries due to Russia's war in Ukraine.

Putin, in power as president or prime minister since 1999, begins his new mandate more than two years after he sent tens of thousands of troops into Ukraine, where Russian forces have regained the initiative after a series of reversals and are seeking to advance further in the east.

At 71, Putin dominates the domestic political landscape. On the international stage, he is locked in a confrontation with Western countries he accuses of using Ukraine as a vehicle to try to defeat and dismember Russia.

"For Russia, this is the continuation of our path, this is stability – you can ask any citizen on the street," Sergei Chemezov, a close Putin ally, told Reuters before the ceremony.

"President Putin was re-elected and will continue the path, although the West probably doesn’t like it. But they will understand that Putin is stability for Russia rather than some sort of new person who came with new policies – either cooperation or confrontation even," he said.

Putin in March won a landslide victory in a tightly controlled election from which two anti-war candidates were barred on technical grounds.

His best known opponent, Alexei Navalny, died suddenly in an Arctic penal colony a month earlier, and other leading critics are in jail or have been forced to flee abroad.

The United States and other Western countries stayed away from Tuesday's inauguration ceremony.

"No, we will not have a representative at his inauguration," Matthew Miller, a U.S. State Department spokesperson, said on Monday.

"We certainly did not consider that election free and fair but he is the president of Russia and he is going to continue in that capacity."

Britain, Canada and most European Union nations also decided to boycott the swearing-in, but France said it would send its ambassador.

Ukraine said the event sought to create "the illusion of legality for the nearly lifelong stay in power of a person who has turned the Russian Federation into an aggressor state and the ruling regime into a dictatorship."

(Reporting by Guy Faulconbridge in Moscow and Mark Trevelyan in London Editing by Andrew Osborn)