President Donald Trump headed into his first summit with Vladimir Putin on Monday determined to forge a personal bond with the Kremlin chief and adamant that only "stupidity" by prior administrations had brought US-Russian ties to their present low.

Hours before the Helsinki summit, Trump was asked if he would press Putin over Russia's alleged manipulation of the 2016 election that brought the mercurial property tycoon to power. He said only: "We'll do just fine."

Democrats had called for the summit's cancellation after new revelations surrounding the election meddling. But Trump has insisted it is "a good thing to meet", as he attempts to replicate with Putin the sort of personal rapport he proclaims with the autocratic leaders of China and North Korea.

If his instinct proves right and the pair find common ground, then the summit may take the heat out of some of the world's most dangerous conflicts including Syria.

But the Washington-Moscow rivalry has rarely been more bitter, and there are many points of friction that could yet spoil Trump's hoped-for friendship.

Trump began the day's talks by meeting Finland's President Sauli Niinisto, who has loaned his harbour-front palace for the occasion. But first he took a moment to fire a Twitter broadside at his domestic opponents, blaming the diplomatic chill on the investigation into Russian election meddling.

"Our relationship with Russia has NEVER been worse thanks to many years of U.S. foolishness and stupidity and now, the Rigged Witch Hunt!" Trump tweeted.

After a stormy NATO summit in Brussels last week, Trump was accused by critics of cosying up to Putin while undermining the alliance.

But, over breakfast with Niinisto, he insisted NATO "has never been stronger" and "never been more together" thanks to his insistence on all allies paying their fair share.

With Washington and Moscow at loggerheads over Ukraine, Iran and trade tariffs as well as Syria, even Trump has cautioned that he is not approaching the Putin summit "with high expectations".

The 72-year-old brash billionaire has been president for 18 months, while the former KGB officer, 65, has run Russia for the past 18 years.

In an interview with CBS News that aired before he touched down in Helsinki, Trump admitted that Russia remains a foe, but he put Moscow on a par with China and the European Union as economic and diplomatic rivals.

AFP / FRANCK FIFE Russia's President Vladimir Putin, shown here alongside an ecstatic French President Emmanuel Macron, was due in Helsinki after hosting the World Cup final

The Kremlin has also played down hopes that the odd couple will emerge from their first formal one-on-one summit with a breakthrough.

Putin, who played host at the World Cup final in Moscow on Sunday and was due to arrive in Finland later Monday, has remained terse in the run-up to the summit.

On Friday his adviser Yuri Ushakov also played down expectations, saying: "The state of bilateral relations is very bad.... We have to start to set them right."

- Giving up ground? -

Indeed, after the bad-tempered NATO summit and a contentious trip by Trump to Britain, anxious European leaders may be relieved if not much comes out of the Helsinki meeting.

Those leaders are already fuming over Trump's imposition of trade tariffs on various countries, including Russia.

European Union President Donald Tusk called on the United States, China and Russia to work together to cool the global trade tensions, warning that they could spiral into violent "conflict and chaos".

For their part, protesters have been on the streets of Helsinki to denounce the policies of both Trump and Putin. Greenpeace draped a giant banner down a church tower urging: "Warm our hearts not our planet."