WASHINGTON — President Donald Trump, pounded by criticism after a summit with Russian strongman Vladimir Putin, insisted Tuesday that he really does believe U.S. intelligence agencies' consensus that Russia meddled in the 2016 election.

But he undermined that explanation by also asserting that "other people" besides Russians could have been involved.

"I accept our intelligence community's conclusion that Russia's meddling in the 2016 election took place," Trump said. But he added, "Could be other people also. A lot of people out there."

The scene at the White House was extraordinary — a contrite and somewhat subdued president reading from a prepared statement, interrupting and then reigniting a barrage against him on cable news networks as he sought to walk back comments made a day earlier in Finland.

He blamed a slip of the tongue at that news conference in Helsinki, saying that left the mistaken impression that he accepted the denial of Putin, a former KGB chief, over the FBI and CIA's assessments that Russian intelligence hacked Democratic Party emails and strategically leaked them to influence the election.

The Justice Department unveiled indictments last week against a dozen Russian officers. It's unclear if Trump pressed Putin for their extradition to stand trial during their hours together on Monday in Finland.

Back in Washington on Tuesday, Trump said he was surprised at the uproar, which raged for the previous 24 hours. After reviewing the transcript and video footage of his remarks at a post-summit news conference with Putin, he said, "I realize that there is a need for some clarification."

"I said the word `would' instead of `wouldn't.' The sentence should have been... `I don't see any reason why it wouldn't be Russia.' Sort of a double negative," he said, adding, "That probably clarifies things."

Trump had been asked whether he believed that Russia was responsible for the hacking.

Lawmakers in both parties blasted Trump for bringing shame on the presidency, showing weakness to Putin and the world. The outpouring of criticism was unusual even for Trump's tumultuous tenure.

"I just wanted to clear up. I have the strongest respect for our intelligence agencies," Trump said Tuesday ahead of a meeting on tax policy with House Ways and Means Chairman Kevin Brady, a Texas Republican, and others.

Trump lauded the summit.

"This was our most successful visit," he said. He said that he and Putin met to "tackle some of the most pressing issues facing humanity. We have never been in a worse relationship with Russia than we were" up to a few days ago. The relationship has improved substantially, he said, as a result of the meeting with Putin."

He called the meeting "really interesting" and deflected criticism of his eagerness to meet with Putin, despite a fuzzy agenda, and the outcome.

"Diplomacy and engagement is better than hostility and conflict," he said.

He emphasized his support for U.S. spy agencies.

"I have full faith and support for America's great intelligence agencies. Always have," Trump said. "While Russia's actions had no impact at all on the outcome of the election... I accept our intelligence community's conclucsion that Russia's meddling int eh 2016 election took place."

There was no collusion at all. People have seen that and they've seen that strongly... I thought that I made myself very clear" having reviewed the transcript.

He vowed to "repel" any future efforts to Russia to interfere in American elections and democracy.

He also complained that coverage of the NATO summit was inaccurate, insisting that he had not been "insulting" toward U.S. allies.

Speaking to reporters at the White House, he insisted that "I have helped the NATO alliance greatly" by prodding allies to spend more on mutual defense. "There's great unity with NATO... There's a great spirit that we didn't have before."