(AP) MOSCOW - Vladimir Putin took the oath of office in a brief Kremlin ceremony on Monday, while on the streets outside thousands of helmeted riot police prevented hundreds of demonstrators from protesting his return to the presidency.
Putin, 59, has ruled Russia since 2000, first as president and then during the past four years as prime minister. The new, now six-year term will keep him in power until 2018, with the option of running for a fourth term.
"I consider service to the fatherland and our nation to be the meaning of my life," Putin said in addressing 3,000 guests in a glittering Kremlin hall.
Despite unprecedented security measures in the center of Moscow, where streets were closed to traffic and passengers prevented from exiting subway stations, at least 1,000 opposition activists tried to protest along the route Putin's motorcade took to the Kremlin. Many wore the white ribbons that are a symbol of the anti-Putin protest movement.
The demonstrators, separated into several groups, were met by helmeted riot police. A total of 120 were detained, including opposition leader Boris Nemtsov.
Putin's inauguration came a day after an opposition protest drew more than 20,000 people, fewer than the mass demonstrations in the months that preceded his March election but still a sign that the anger over Putin's return to the Kremlin has not faded.
Sunday's protest turned violent when some demonstrators tried to march toward the Kremlin and riot police beat back the crowds with batons and detained more than 400 people. The use of force after the winter's peaceful rallies indicate that Putin may take a harder line toward the protesters now that he is once again president.
"We want to live and we will live in a democratic country where everyone has the freedom and opportunity to apply their talent and labor, their energy. We want to live and we will live in a successful Russia, which is respected in the world as a reliable, open, honest and predictable partner."
During his time in office, Putin has overseen dramatic economic growth and restored a sense of national pride after the instability and humiliations that followed the 1991 collapse of the Soviet Union. He also has retreated from the democratic achievements of the 1990s and imposed a political system that has stifled dissent.
Dmitry Medvedev, who served as Russia's president for the past four years as Putin's junior partner, wrapped up his term with a short speech at the inauguration ceremony.
"I worked as I promised in taking the oath of office: openly and honestly in the interests of the people, doing everything I could so that they would be free and would look toward the future with confidence," Medvedev said.
Putin was expected to formally nominate Medvedev as his prime minister on Tuesday.