U.S. President Donald Trump said after meeting Russian President Vladimir Putin on Monday in Helsinki that he didn't see "any reason why" Russia would have interfered in the 2016 U.S. federal election, despite the findings of his own intelligence agencies.

On a day when he faced pressure from critics, allied countries and even his own staff to take a tough line, Trump said not a single critical word about Moscow on any of the issues that have brought relations between the two powers to the lowest ebb since the Cold War.

Instead, he denounced the "stupidity" of his own country's policy, especially the decision to investigate election interference. Trump's performance is likely to create a political storm in the United States, where the White House has struggled for months to dispel a suggestion that Trump was unwilling to stand up to Putin.

Trump held his meeting with Putin just days after a special prosecutor in the United States indicted 12 Russian agents for stealing Democratic Party documents to help him win the vote. Asked if he believed U.S. intelligence agencies, which concluded that Russia interfered in the 2016 election to help him defeat Democratic candidate Hillary Clinton, he said he was not convinced.

Watch as Trump deflects a direct question about Russian election interference.

Blames Democrats and Hillary Clinton, and says he believes Vladimir Putin's denial of any wrongdoing 4:41

"I don't see any reason why it would be" Russia, Trump said.

"President Putin was extremely strong and powerful in his denial today."

The U.S. president also continued to deny that there had been any other collusion between his campaign and Russians, declaring: "We ran a brilliant campaign and that's why I'm president."

Speaking through an interpreter, Putin once again denied what he described as "so-called interference of Russia." He called it "nonsense" and insisted the Russian state had never interfered and would never interfere in the American electoral process.

Trump and Putin attend a working lunch during their meeting on Monday. (Pablo Martinez Monsivais/Associated Press)

Putin said the meeting marked the first steps to restore "an acceptable level of trust and go back to previous level of interaction on all mutual interest issues."

The Russian president reiterated his message in an interview with Chris Wallace of Fox News, saying allegations of meddling were ridiculous and that Russia had nothing compromising on Trump.

Russian President Putin on the Mueller probe: I'm not interested in this issue a single bit. It's the internal political games of the United States. <a href="https://twitter.com/hashtag/WallacePutinOnFox?src=hash&ref_src=twsrc%5Etfw">#WallacePutinOnFox</a> <a href="https://t.co/OqrOzjYveR">https://t.co/OqrOzjYveR</a> <a href="https://t.co/xejkVcxb8C">pic.twitter.com/xejkVcxb8C</a> —@FoxNews

"I don't want to insult President Trump when I say this — and I may come as rude — but before he announced that he will run for presidency, he was of no interest for us," he said in the Fox interview.

'Clear in our assessment'

American intelligence agencies have said their assessments show that Russia meddled in the 2016 campaign.

In a statement released after the meeting between the two leaders, Director of National Intelligence Daniel Coats — who was appointed by Trump — said the role of the intelligence community is "to provide the best information and fact-based assessments possible" for the president and U.S. policymakers.

"We have been clear in our assessment of Russian meddling in the 2016 election and their ongoing, pervasive efforts to undermine our democracy, and we will continue to provide unvarnished and objective intelligence in support of our national security.

As reaction and criticism poured in after the meeting, the U.S. president weighed in again on Twitter later Monday, saying "as I said today and many times before, "I have GREAT confidence in MY intelligence people." However, I also recognize that in order to build a brighter future, we cannot exclusively focus on the past — as the world's two largest nuclear powers, we must get along!"

'Foolishness and stupidity'

Before the summit even began, Trump blamed his own country for the deterioration in relations.

"Our relationship with Russia has NEVER been worse thanks to many years of U.S. foolishness and stupidity and now, the Rigged Witch Hunt!" he said on Twitter. The Russian foreign ministry tweeted back: "We agree."

At the news conference, Trump was invited by reporters to offer any criticism of Russia but he repeatedly declined.

Asked if Russia was at all to blame for the poor ties, he said: "I hold both countries responsible. I think the U.S. has been foolish. We've all been foolish," he said, before veering into discussion about his election victory.

Watch as Trump blames both U.S. and Russia for the frosty relations between the 2 nations.

'I think that the United States has been foolish,' U.S. president says at Helsinki news conference 2:00

"I beat Hillary Clinton easily and frankly we beat her. We won that race and it's a shame that there can be even a little bit of a cloud over it," he said.

Trump's warm words for Russia were a marked contrast from the past week when he repeatedly rebuked traditional U.S. allies at a summit of NATO and during a visit to Britain.

Asked if Putin was an adversary, he said: "Actually I called him a competitor and a good competitor he is and I think the word competitor is a compliment."

Putin spoke of the importance of the two countries working together and praised Trump, at one point interrupting the news conference to give the U.S. president a soccer ball.

Asked whether he had wanted Trump to win the 2016 election and had instructed officials to help him, Putin said, "Yes I did," although he denied any interference, saying the allegations were "complete nonsense."

Trump also told gathered reporters that Putin made an "incredible offer" of law enforcement collaboration during the leaders' one-on-one summit.

Watch the full Trump-Putin news conference below.

U.S. President Donald Trump and Russian President Vladimir Putin speak to reporters following their meeting in Helsinki on Monday. 45:50

Putin said American investigators who have charged 12 Russians with hacking during the 2016 presidential election can come work with Russian investigators on the case.

A spokesperson for special counsel Robert Mueller, whose office on Friday charged the hackers, declined to comment.

It was not clear from Trump's statement what sort of help Putin was offering. The United States does not have an extradition treaty with Russia, making it uncertain that the indicted Russian military intelligence officers will ever be prosecuted in an American courtroom.

The summit, which is being closely watched around the world, was not the first time Trump and Putin have held talks. They met on the sidelines of world leader meetings in Germany and Vietnam last year.