Vladimir Putin took the oath as Russia's president today with a ringing appeal for unity at the start of a six-year term in which he faces growing dissent, economic problems and bitter political rivalries.
Putin, 59, was sworn in with his right hand resting on the Russian constitution in a glittering ceremony in the Kremlin's former throne room attended by 2,000 dignitaries who applauded his every step along a long red carpet to the podium.
Outside the Kremlin's high red walls, police rounded up men and women in cafes wearing the white ribbons symbolising their growing protest movement against Putin, having detained more than 400 people during clashes with protesters on Sunday.
"We will achieve our goals if we are a single, united people, if we hold our fatherland dear, strengthen Russian democracy, constitutional rights and freedoms," Putin said in a five-minute speech after taking the oath.
"I will do all I can to justify the faith of millions of our citizens. I consider it to be the meaning of my whole life and my obligation to serve my fatherland and our people."
The former KGB spy will also be blessed by the head of the Russian Orthodox Church and take charge of the nuclear suitcase before hosting a lavish reception.
Although he has remained Russia's dominant leader for the past four years as prime minister, Putin has now taken back the formal reins of power he ceded to his ally Dmitry Medvedev in 2008 after eight years as president.
But he is returning with his authority weakened by months of protests that have polarised Russia and left him facing a battle to reassert himself or risk being sidelined by the powerful business and political elites whose backing is vital.
Riot police detained at least 22 protesters when a crowd of more than 100 started shouting "Russia without Putin" near two exclusive hotels 500 metres from the Kremlin shortly before the inauguration. Bystanders shouted "Shame" as they did so.
"This shows that Putin is scared of dissatisfied citizens. Although there are not so many of us, there are not so few either," said 18-year-old student Pavel Kopilkov.
At least 20 others were detained by police on a boulevard near the route of Putin's motorcade to the ceremony, including some who had been sitting outside a French bistro wearing the white ribbon of protest on their jackets and coats.
A Reuters correspondent saw tables and chairs being overturned as the people were hauled away.
"This is shameful. This is not how you celebrate a holiday - this is how you celebrate seizing power," liberal opposition leader Boris Nemtsov said shortly after he was detained.
Moscow police said about 120 people had been detained for staging unsanctioned pickets and most would soon be released. In Putin's hometown of St. Petersburg, police detained a few people in a crowd of dozens at a protest on the central Palace Square.