MUNICH, Germany (AP) -- Russian President Vladimir Putin blasted the United States Saturday for the "almost uncontained" use of force in the world, and for encouraging other countries to acquire nuclear weapons.
He also criticized U.S. plans for missile defense systems and NATO's expansion.
Putin told a security forum attracting top officials that "we are witnessing an almost uncontained hyper use of force in international relations" and that "one state, the United States, has overstepped its national borders in every way.
"This is very dangerous, nobody feels secure anymore because nobody can hide behind international law," Putin told the gathering.
Putin did not elaborate on specifics and did not mention the wars in Iraq or Afghanistan.
But he voiced concern about U.S. plans to build a missile defense system in eastern Europe -- likely in Poland and the Czech Republic -- and the expansion of NATO as possible challenges to Russia.
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 response.
"That balance will be upset completely and one side will have a feeling of complete security and given a free hand in local, and probably in global, conflicts..." he said. "We need to respond to this."
"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."
He also dismissed suggestions that the European Union and NATO had the right to intervene alone in crisis regions. "The legitimate use of force can only done by the United Nations, it cannot be replaced by EU or NATO," he said.
Putin's comments to a weekend forum attended by 250 officials, including Defense Secretary Robert Gates and Iranian nuclear negotiator Ali Larijani, came after German Chancellor Angela Merkel said that the international community is determined to prevent Iran from obtaining nuclear weapons.
Merkel said Tehran needed to accept demands made by the U.N. and the International Atomic Energy Agency.
"There is no way around this," Merkel said. "What we are talking about here is a very, very sensitive technology, and for that reason we need a high degree of transparency, which Iran has failed to provide, and if Iran does not do so then the alternative for Iran is to slip further into isolation."
Merkel, whose country holds the rotating European Union presidency, emphasized the international community's support for Israel and said there was a unified resolve to prevent Iran from developing nuclear weapons.
"We are determined to prevent the threat posed by an Iranian military nuclear program," she said.
The annual Munich Conference on Security Policy, now in its 43rd year, is often used as an opportunity for officials to conduct diplomacy in an informal setting.
Some 3,500 police were on hand to provide tight security for the conference and kept the usual throng of demonstrators away. This year, several thousand protesters were expected, protest organizers said.
Heading in to the conference, Larijani, who is scheduled to speak on Sunday, said he planned to use the conference as an opportunity to talk about Iran's nuclear program. Those would be the first talks with Western officials since limited U.N. sanctions were imposed on the country in December, which fell short of harsher measures sought by the United States.
Larijani was expected to meet with German Foreign Minister Frank-Walter Steinmeier and Javier Solana, the EU's chief foreign policy envoy.
At the opening dinner on Friday, Israeli Foreign Minister Tzipi Livni urged international solidarity in putting pressure on Iran to prevent it from producing a nuclear weapon.
"It is a regime that mocks the Holocaust while threatening the world with a new one, while trying to develop a weapon to do so," she said. "Iran is a threat not only to Israel ... but to the world. The international community cannot show any hesitation ... Any hesitation on our part is being perceived as weakness."
The conference this year focuses on "Global Crises -- Global Responsibilities," looking at NATO's changing role, the Middle East peace process, the West's relations with Russia and the fight against terrorism.
Merkel opened the conference telling the delegates that one of the major threats facing the world today is global warming, urging a combined effort to combat it.
"Global warming is one of the major medium- to long-term threats that could have a dramatic effect," Merkel said.
Gates, who planned to talk Sunday on trans-Atlantic relations, was expected to press allies for more troops and aid for a spring offensive in Afghanistan.
He delivered the message Friday to a NATO defense minister's meeting in Seville, Spain, but got a lukewarm response.
France and Germany are questioning the wisdom of sending more soldiers, while Spain, Italy and Turkey have also been wary of providing more troops.