Russian President Vladimir Putin on Saturday blamed U.S. policy for inciting other countries to seek nuclear weapons to defend themselves from an "almost uncontained use of military force" — a stinging attack that underscored growing tensions between Washington and Moscow.
"Unilateral, illegitimate actions have not solved a single problem, they have become a hotbed of further conflicts," Putin said at a security forum attracting senior officials from around the world.
"One state, the United States, has overstepped its national borders in every way."
The Bush administration said it was "surprised and disappointed" by Putin's remarks. "His accusations are wrong," said Gordon Johndroe , Bush's national security spokesman.
In what the Russian leader's spokesman acknowledged was his harshest criticism of the United States, Putin attacked Bush's administration for stoking a new arms race by planning to deploy a missile defense system in eastern Europe and for backing a U.N. plan that would grant virtual independence to Serbia's breakaway province of Kosovo.
Sen. John McCain, R-Ariz., who was also attending the conference, described Putin's remarks as "the most aggressive speech from a Russian leader since the end of the Cold War."
The United States and an increasingly assertive Russia repeatedly have butted heads during the past year, with Vice President Dick Cheney accusing Moscow of using its energy resources as "tools of intimidation or blackmail." Washington also has been angered by Russia's reluctance to impose meaningful sanctions against Iran, which is accused of seeking to develop nuclear weapons under the cover of a civilian atomic energy program.
But Putin said it was "the almost uncontained hyper use of force in international relations" that was forcing countries opposed to Washington to seek to build up nuclear arsenals.
"It is a world of one master, one sovereign ... it has nothing to do with democracy," he said. "This is nourishing the wish of countries to get nuclear weapons."
"This is very dangerous, nobody feels secure anymore because nobody can hide behind international law," Putin told the gathering.
Putin did not mention the wars in Iraq or Afghanistan, but he voiced concern about NATO's expansion plans as possible challenges to Russia.
"The process of NATO expansion has nothing to do with modernization of the alliance or with ensuring security in Europe," Putin said. "On the contrary, it is a serious factor provoking reduction of mutual trust."
On the missile defense system, Putin said: "I don't want to accuse anyone of being aggressive" but suggested it would seriously change the balance of power and could provoke an unspecified "asymmetric" response.
On Kosovo, Moscow has said a solution imposed against Serbia's consent could serve as a model for other separatist provinces elsewhere in the world. Washington, which supports Kosovo's independence, maintains that the Kosovo situation is a "one-off" because the province has been under U.N. rule since 1999 when Serb forces were ejected following a brief aerial war with NATO.
U.S. Defense Secretary Robert Gates had little to say about the accusations, remarking only that Putin "was very candid."
NATO Secretary General Jaap de Hoop Scheffer said he was disappointed by Putin's criticism about NATO expansion. "Who can be worried that democracy and the rule of law is coming closer to somebody's border?" he asked.
Putin's spokesman Dmitry Peskov said the president's speech was not "confrontational" and attributed his blunt words to the sense that the number of conflicts fomented by Washington "was constantly growing" and that international law was being undermined by such actions.
"It is in the interest of the United States, the European Union and other countries that international law is upheld, not further destroyed," Peskov said.
Minutes earlier, German Chancellor Angela Merkel — whose country holds the European Union's rotating presidency — had praised Russia, saying it would be a reliable energy supplier to Europe. She called for closer relations between the EU and Moscow to enhance stability on the continent.
"How relations between the EU and Russia evolve will have a crucial impact on how security in the region will develop," Merkel told the annual Munich Conference on Security Policy. The forum is often used as an opportunity for officials to conduct diplomacy in an informal setting.
Russia's reputation as a supplier of natural gas to the West was damaged in the recent past when it halted supplies to Europe through main pipelines crossing Belarus and Ukraine due to pricing disputes with those two countries.
Merkel also said that the international community is determined to prevent Iran from obtaining nuclear weapons. Tehran needed to accept demands made by the U.N. and the International Atomic Energy Agency, she said.
On the sidelines of the conference, Iranian nuclear negotiator Ali Larijani defended his country's nuclear program as peaceful, saying: "We are no threat to our region or other countries," while indicating a willingness to return to negotiations.
Get complete coverage in FOXNews.com's Europe Center.