Berlin (AFP) - German Chancellor Angela Merkel on Monday warmly offered to cooperate closely with Joe Biden after his election as America's next president, a sharp contrast to her stern warning to Donald Trump four years ago.

Underlining the President-elect's "decades of experience in foreign policy" and recalling "good encounters and talks with him", Merkel vowed to "stand together" with Washington to overcome international challenges from the coronavirus pandemic to global warming.

The marked change in tone to Trump's 2016 victory, which Merkel had greeted with an extraordinary warning over democratic values, came as Germany heaved a sigh of relief at Biden taking the White House even if differences with Washington are expected to persist under the Democrat.

Merkel notably left the US billionaire leader and his administration completely out of her message on the US election.

Be it over military spending or Germany's strong exports, Trump, who is still contesting the US polls result, has made no effort to hide his ire towards Europe's biggest economy.

But it was his contempt of international treaties and multilateralism as he championed "America First" that deeply shocked Germans.

Trump ripped up the Iran nuclear treaty early in his term, slapped tariffs on EU steel and aluminium, and as Americans went to the polls last week, the US formally left the Paris Climate Agreement.

Hailing Biden's victory, German leaders have rushed to urge him to make good on his pre-election promise to reinstate the US on the climate treaty again.

"The return of the US to these common ideals offers the opportunity to stop the erosion of the international order," wrote German President Frank-Walter Steinmeier in an editorial for the Frankfurter Allgemeine Zeitung.

"With a return to the Paris climate agreement, renewed cooperation in the World Trade Organization, in the North Atlantic Treaty Organization and also in curbing Iran's nuclear programme, the USA can once again counter the threat of international anarchy in which only 'maximum pressure' counts, with a more optimistic vision of our common future," he added.

At the same time, Steinmeier underlined that four years of Trump have also taught Germany the lesson that Europe needed to stand on its own feet rather than wait for its transatlantic partner to take the lead.

A point echoed by Merkel who said Europeans would do more to pull their own weight.

More responsibility

"Germans and Europeans know that we must take on more responsibility in this partnership in the 21st century," said Merkel, whose country holds the rotating presidency of the EU.

"America is and remains our most important ally but it expects us, and rightly so, to boost our efforts and to ensure our own security and to stand up for our own convictions in the world," added the German leader, who will step down next year.

The pragmatism came as analysts noted that not all of Europe's interests may dovetail with those of the US.

Areas of friction will likely remain on military spending, the controversial Russia-to-Europe gas pipeline Nord Stream 2, and Washington's campaign against Chinese tech giant Huawei.

German Foreign Minister Heiko Maas, who promised a new start in transatlantic relationships, a "new deal", said Berlin will make "concrete proposals on how we can close ranks -- in dealings with players like China" for instance.

But faced with a Covid-19 battered economy, Biden may well eschew Trump's protectionist tendencies while allowing some sort of "America First" vision for sensitive industries to live on.

Economy Minister Peter Altmaier himself warned that "specific sectors in the US have increased their competitiveness through tariffs... and Joe Biden will not take this lightly either".

Foreign policy veteran Wolfgang Ischinger, who chairs the Munich Security Conference, also noted that things won't "simply be all good" again between Europe and the US under Biden.

Washington is expected to keep a critical eye on Germany's softer approach with China and Berlin's reluctance to let go of Nord Stream 2 which critics believe would give Russia too much control.

Nevertheless, a key difference lies in attitudes.

"We would be able to tackle these problems together on the basis of a more trustworthy relationship between leaders," said Ischinger.