US President Donald Trump and first lady Melania Trump arrive at Helsinki-Vantaa airport in Vantaa, Finland on July 15, 2018. (Photo: VCG)

Hours before he was due to sit down for his first ever summit with Vladimir Putin, US President Donald Trump blamed "US foolishness" for bad relations between Washington and Moscow, while the Kremlin said it expected a tough meeting.

Trump's comments show how much domestic political pressure he is under over the meeting in the Finnish capital Helsinki, while the Kremlin's gloomy comments reflect its belief that the fact the summit is even happening is a win for Russia.

Critics and his own advisers have urged Trump to use the summit to press Putin hard about election meddling and other "malign" activities.

But hours before he was due to meet the Russian president, Trump focused his ire on his own country and the investigation into possible links between his 2016 campaign and Russia. The president has denied any collusion took place.

"Our relationship with Russia has NEVER been worse thanks to many years of US foolishness and stupidity and now, the Rigged Witch Hunt!" Trump wrote on Twitter, referring to the investigation into possible collusion.

During a breakfast meeting Finland's president before the meeting with Putin in the Finnish capital, Trump appeared upbeat.

Asked what he would say to the Russian president, Trump said: "We'll be just fine, thank you."

Trump also repeated his belief that predecessor Barack Obama had failed to act on Russian meddling.

While Trump has been abroad since last week, the special prosecutor investigating allegations that Russia interfered to help Trump win the 2016 presidential election indicted 12 Russians on Friday for stealing Democratic Party documents.

Trump's foes at home have been scathing about his apparent refusal to criticize Putin.

His 2016 opponent Hillary Clinton tweeted: "Great World Cup. Question for President Trump as he meets Putin: Do you know which team you play for?"

For Putin, the fact that the summit is even happening despite Russia's semi-pariah status among some Americans and US allies is a geopolitical win because, in Russian eyes, it shows that Washington recognizes Moscow as a great power that cannot be isolated or ignored.

The Kremlin made clear beforehand it did not expect an easy meeting, taking Trump to task over his criticism of a planned Russian gas pipeline to Germany and suggesting it would be hard to find common ground on Syria because of differences over Iran.

Trump wants Russia to help Moscow to use its influence in Syria where it is backing President Bashar al-Assad militarily to push Iranian and Iranian-allied forces out.

Russia hoped however that the summit would be "the first step" in overcoming a crisis in relations, he said.

"Presidents Trump and Putin respect each other and they get along well. There is no clear agenda. It will be determined by the heads of state themselves as they go along."

Trump has spoken vaguely about the possibility of halting NATO war games in the Baltic region, and has said repeatedly that it would be good if he could get along with Russia.