The new US administration is determined to strike a new tone in its relations around the world, Vice-President Joe Biden has told a major security forum.
It also wants to press the "reset button" in ties with Russia after a "dangerous drift" in recent years, and was open to talks with Iran, he said.
But while the US was ready to do more, it would expect more from its partners.
The new US vice-president also warned no strategy in Afghanistan could succeed without Pakistan.
He said that the deteriorating situation in the region was a security threat for all countries, not just the US.
Mr Biden's wide-ranging speech to international leaders and security experts in Munich set out foreign policy directions for the Obama administration and also covered climate change and the global economic crisis.
"I come to Europe on behalf of a new administration determined to set a new tone in Washington, and in America's relations around the world," Mr Biden said.
"We will engage. We will listen. We will consult. America needs the world, just as I believe the world needs America," he said.
The US and Russia can disagree and still work together where our interests coincide and they coincide in many places
"Our administration has set ambitious goals... to advance democracy not through its imposition by force from the outside, but by working with moderates in government and civil society to build the institutions that will protect freedom."
On Russia, Mr Biden said: "It's time, to paraphrase President Obama, to press the reset button and to revisit the many areas where we can and should work together."
It would not be possible for the US and Russia to agree on everything "but the United States and Russia can disagree and still work together where our interests coincide and they coincide in many places."
He added that the US would continue with its plans for a missile defence shield in Central Europe.
Amid cool relations between the two states, Mr Biden is expected to have a challenging meeting in Munich with Russian Deputy Prime Minister Sergei Ivanov.
Analysts have portrayed Kyrgyzstan's decision this week to close the last remaining US air base in Central Asia - vital for operations in Afghanistan - as being the work of the Kremlin.
On Iran, Mr Biden said: "We will continue to develop missile defences to counter a growing Iranian capability, provided the technology is proven to work and cost effective."
The old carrot and stick policy must be discarded
Ali Larijani Iranian delegate
He added: "We will do so in consultation with our Nato allies and Russia."
He reiterated President Barack Obama's pledge to communicate with Iran, saying the US offered a clear choice: "Continue down your current course and there will be pressure and isolation; abandon your illicit nuclear programme and support for terrorism and there will be meaningful incentives."
Promising to consult with nations on a range of other issues, Mr Biden also said that the US would "ask for more from our partners", for example in taking former inmates from Guantanamo Bay when the US military prison is closed in a year.
Also at the forum, Nato's chief criticised European countries for not heeding the US call for more troops in Afghanistan.
Secretary-general Jaap de Hoop Scheffer said European countries should "share the heavy lifting," Associated Press news agency reported.
"I'm frankly concerned when I hear the United States is planning a major commitment for Afghanistan but other allies are already ruling out doing more," he said, without specifying which allies.
The French and German leaders both attended the forum
"That is not good for the political balance ... and it also makes the calls for Europe's' voice to be heard in Washington perhaps a bit more hollow than they should be."
His comments come as the BBC learns that the Italian government has decided to increase its contribution to Nato forces in Afghanistan by 800 to 2,800 troops this year.
Iranian delegate Ali Larijani earlier welcomed the new US government, saying it was a "golden opportunity" to improve ties.
But Mr Larijani, who is Iran's parliamentary speaker, warned it would take more than a change of tone and a few interviews from President Obama's government to mend the fractured relationship between Tehran and Washington.
"The old carrot and stick policy must be discarded," he said, referring to Western threats and offers of rewards to coax Iran to give up nuclear activities.
He said the US needed to change its tactics "to a chess game from a boxing match".
The BBC's defence correspondent, Rob Watson, at the conference, says Mr Larijani's comments are a sign that any efforts at reconciliation with Iran will be difficult and complex.
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