President Bush is in Moscow for a four-day visit that will include the signing of a landmark arms treaty that will reduce each country's nuclear arsenals.
Mr. Bush was given a formal state welcome on his arrival at Vnukovo airport. Deputy Prime Minister Aleksey Kudrin greeted the president and Mrs. Bush while an honor guard passed in review.
The airport ceremony was in sharp contrast to anti-American demonstrations in Moscow and St. Petersburg, where protesters burned the American flag and denounced George Bush.
Minor scuffles broke out in both cities. In Moscow police briefly detained several protesters as several hundred demonstrators tried to advance on the American embassy shouting "Yankee Go Home."
In St. Petersburg a few dozen protesters trampled an American flag while holding aloft an Iraqi flag.
A few hours earlier, in an address to the German parliament, Mr. Bush called Iraq's Saddam Hussein and his quest for weapons of mass destruction a threat to all civilization. His speech drew mild heckling but was otherwise generally well received.
Security has been increased at all major buildings in Moscow and St. Petersburg, along with the international airports and border checkpoints.
The highlight of the Putin-Bush summit will be the signing Friday of a new arms reduction pact that will cut America's and Russia's long-range nuclear arsenals by two-thirds.
In a statement broadcast on Russian television in advance of the visit, Mr. Bush said it is important to show the world that the United States and Russia are no longer enemies, and that neither side is, as he put it, "clinging to our stocks of these terrible weapons." He said a new relationship is developing between the two countries.
Mr. Bush and President Putin have developed a warm personal relationship that analysts here say has gone a long way to improving ties.
Since the September 11 attacks on the United States, Mr. Putin has stood firmly behind the American-led war on terrorism.
But there are a number of unresolved issues that stand in the way of even closer ties. Chief among them are American concerns about possible nuclear technology transfers from Russia to Iran and other countries that Washington has described as rogue states.
Other problems involve Russian opposition to Mr. Bush's plan to develop a national missile system, and trade issues led by the U.S. decision to increase tariffs on certain steel imports and Russian restrictions on U.S. poultry imports.