Just a few months short of a quarter-century as Russia's leader, Vladimir Putin on Tuesday will put his hand on a copy of the constitution and begin another six-year term as president wielding extraordinary power. Since becoming acting president on the last day of 1999, Putin has shaped Russia into a monolith — crushing political opposition, running independent-minded journalists out of the country and promoting an increasing devotion to prudish “traditional values” that pushes many in society into the margins. With that level of power, what Putin will do with his next term is a daunting question at home and abroad.