Russian President Vladimir Putin launched a full-frontal attack on the United States, saying it had broken from international law and made the world a more dangerous place.
Putin's denunciation of US policy, made at a high-level security conference in Munich, prompted dismay among senior officials and politicians from the United States and the North Atlantic Treaty Organisation (NATO).
The United States had disastrously "overstepped" its borders, said the Russian leader, who spearheaded international opposition to the 2003 US-led invasion of Iraq, which was also opposed by Germany and France.
"The United States has overstepped its borders in all spheres -- economic, political and humanitarian and has imposed itself on other states," Putin said at the annual Munich Conference on Security Policy.
What he called a "uni-polar" world dominated by the United States, "means in practice one thing: one centre of power, one centre of force, one centre of decision-making, a world of one master, one sovereign," Putin said.
Such a situation was "extremely dangerous. No one feels secure because no one can hide behind international law."
In a first reaction, the White House said it was surprised and disappointed by Putin's charges.
White House national security spokesman Gordon Johndroe said: "We are surprised and disappointed with President Putin's comments."
"His accusations are wrong," he said.
"We expect to continue cooperation with Russia in areas important to the international community such as counter-terrorism and reducing the spread and threat of weapons of mass destruction," Johndroe said.
In his remarks Putin said US dominance was "ruinous, not only for those inside the system but for the sovereign himself because it destroys him from within. It has nothing in common with democracy."
In a direct reference to US military policy, Putin said "local and regional wars didn't get fewer. The number of people who died didn't get less, but increased.... We see no kind of restraint, a hyper-inflated use of force."
The United States, he said, had gone "from one conflict to another without achieving a fully-fledged solution to any of them."
Putin also rejected US criticism that Russia has back-tracked on democracy during his period as president.
"They are permanently teaching Russia about democracy. But those who teach us, for some reason don't really want to study it themselves."
The Russian leader particularly criticised US plans to site a missile defence system close to Russia's border in NATO countries the Czech Republic and Poland, and made clear his opposition to any further NATO enlargement.
"Why is it necessary to put military infrastructure on our border? It's hardly connected to today's global threats. What is the real threat? Terrorism," Putin said.
The speech marked a further worsening of relations between Moscow and Washington under Putin, who has tried to restore Russia's prestige since the economic collapse that followed the breakup of the Soviet Union in 1991.
Russian officials have accused Washington of sparking a new arms race due to the US plans for missile defence facilities in the Czech Republic and Poland.
A spokesman for Putin, Dmitry Peskov, said the speech "is not about confrontation, but an invitation to think."
But Putin's words were strongly criticised by NATO Secretary General Jaap de Hoop Scheffer and Senator and presidential hopeful John McCain (R-AZ).
De Hoop Scheffer said: "I can't hide my disappointment. I will not hide my disappointment. It's not helpful."
McCain insisted "today's world is not uni-polar."
"The US did not single-handedly win the Cold War.... The transatlantic alliance won the Cold War," McCain said.
"Russian leaders' apparent belief to the contrary raises a number of very difficult questions," he said.
US Defence Secretary Robert Gates was due to make his first major speech since taking office at the conference on Sunday.
Also in the spotlight was Iran's top nuclear negotiator, Ali Larijani, who was due to address the meeting after Gates.
German Chancellor Angela Merkel told the conference the international community was resolved to prevent Iran from developing nuclear weapons, an aim that Iran denies harbouring.
"We are all determined to prevent the threat of an Iran with a military nuclear programme," Merkel said.
Larijani has said he will also meet European officials in Munich, who, it is believed, will try to get Iran to re-engage in talks over its nuclear programme.
Several thousand anti-war protesters marched through the southern German city to demonstrate against the conference, police said.