Munich: US Vice President Mike Pence on Saturday brought a message of support for Europe from Donald Trump but failed to wholly reassure allies worried about the new president's stance on Russia and the European Union.

In Pence's first major foreign policy address for the Trump administration, the vice president told European leaders and ministers that he spoke for Trump when he promised "unwavering" commitment to the NATO military alliance.

"Today, on behalf of President Trump, I bring you this assurance: the United States of America strongly supports NATO and will be unwavering in our commitment to this transatlantic alliance,"Pence told the Munich Security Conference.

While Poland's defence minister praised Pence, many others, including France's foreign minister and U.S. lawmakers in Munich, remained sceptical that he had convinced allies that Trump, a former reality TV star, would stand by Europe.

Trump's contradictory remarks on the value of the North Atlantic Treaty Organisation, scepticism of the 2015 deal to curb Iran's nuclear ambitions and an apparent disregard for the future of the European Union have left Europe fearful for the seven-decade-old U.S. guardianship of the West.

French Foreign Minister Jean-Marc Ayrault on Twitter expressed his disappointment thatPence's speech contained "Not a word on the European Union", although the vice president will take his message to EU headquarters in Brussels on Monday.

U.S. Senator Chris Murphy, a member of the opposition Democrats, said he saw two rival governments emerging from the Trump administration.

Pence, Trump's defense secretary Jim Mattis and his foreign minister Rex Tillerson all delivered messages of reassurance on their debut trip to Europe.

But events in Washington, including a free-wheeling news conference Trump gave in which he branded accredited White House reporters "dishonest people", sowed more confusion.

"Looks like we have two governments," Murphy wrote on Twitter from Munich. The vice president "just gave speech about shared values between US and Europe as (the U.S. president) openly wages war on those values."

The resignation of Trump's security adviser Michael Flynn over his contacts with Russia on the eve of the U.S. charm offensive in Europe also tarnished the message Pence, Mattis and Tillerson were seeking to send, officials told Reuters.

U.S. Republican Senator John McCain, a Trump critic, told the conference on Friday that the new president's team was "in disarray," breaking with the American front.

The United States is Europe's biggest trading partner, the biggest foreign investor in the continent and the European Union's partner in almost all foreign policy, as well as the main promoter of European unity for more than sixty years.

Pence, citing a trip to Cold War-era West Berlin in his youth, said the new U.S. government would uphold the post-World War Two order.

"This is President Trump's promise: we will stand with Europe today and every day, because we are bound together by the same noble ideals – freedom, democracy, justice and the rule of law," Pence said.

MUTED APPLAUSE

While the audience listened intently, Pence received little applause beyond the warm reception he received when he declared his support for NATO.

Ayrault, in a speech defending Franco-German leadership in Europe, lauded the virtues of multilateralism at a time of rising nationalism. Trump has promise 'America First.'

"In these difficult conditions, many are attempting to look inward, but this isolationism makes us more vulnerable. We need the opposite," Ayrault said.

Pence warned allies they must pay their fair share to support NATO, noting many lack "a clear or credible path" to do so. He employed a tougher tone than Mattis, who delivered a similar but more nuanced message to NATO allies in Brussels this week, diplomats said.

The United States provides around 70 percent of the NATO alliance's funds and European governments sharply cut defence spending since the fall of the Soviet Union. Russia's resurgence as a military power and its seizure of Ukraine's Crimean peninsula in the Black Sea has started to change that.

Baltic states and Poland fear Russia might try a repeat of Crimea elsewhere. Europe believes Moscow is seeking to destabilize governments and influence elections with cyber attacks and fake news.

Pence's tough line on Russia, calling Moscow to honour the international peace accords that seek to end the conflict in eastern Ukraine, were welcomed by Poland.

"Know this: the United States will continue to hold Russia accountable, even as we search for new common ground, which as you know, President Trump believes can be found," Pence said.

Polish Defence Minister Antoni Macierewicz said Pence's speech "highlighted on behalf of President Trump that the U.S. supports NATO, Ukraine and Europe.

"They want to show the U.S. military potential," he said.