Donald Trump, then the president-elect, meeting with President Barack Obama in the Oval Office on November 10. REUTERS/Kevin Lamarque

President Donald Trump on Thursday refused to say that Russia had undoubtedly interfered in the 2016 election, instead pivoting to attack former President Barack Obama during a press briefing with Polish President Andrzej Duda in Warsaw, Poland.

"I think it could very well have been Russia," Trump told reporters, adding: "But I think it could well have been other countries. I won't be specific. But I think a lot of people interfere ... It's been happening for many, many years."

Trump then accused Obama of doing "nothing" in response to intelligence reports last summer that pointed to Russian interference.

"The thing I have to mention is that Barack Obama when he was president found out about this in terms of if it were Russia," Trump said. "Found out about it in August. Now the election was in November. That's a lot of time. He did nothing about it. Why did he do nothing about it?"

Trump was referring to the fact that the Obama administration waited until October 7 to publicly identify Russia as being behind the hacking of Democratic Party organizations, even though the CIA had informed the White House of this intelligence as early as August.

"They say he choked. I don't think he choked," Trump said, referring to reporting that a senior Obama administration official felt the White House "choked" in its reaction to the revelations. "He thought Hillary Clinton was going to win the election and he said let's not do anything about it."

Trump added that Obama would have acted more aggressively had he expected Clinton to lose.

"If he thought I was going to win, he would have done plenty about it," Trump said.

In December, Obama made public that he had confronted Russian President Vladimir Putin about the meddling in September, telling him to "cut it out," but Obama said he was loath to appear as if he were attempting to influence the outcome of the election by discussing it publicly.

"Part of the goal here was to make sure we did not do the work of the leakers for them by raising more and more questions about the integrity of the election right before the election was taking place at a time when the president-elect himself was facing questions about the integrity of the election," Obama said.

When a reporter on Thursday asked Trump whether he disagreed with the conclusion of the intelligence community, the president responded that his administration had done "some heavy research" and determined that only "three or four" agencies were in agreement on the evidence on interference.

"Nobody really knows — nobody really knows for sure," Trump said.

Trump could have been referring to a January report in which four American intelligence agencies — the FBI, the CIA, the office of the Director of National Intelligence, and the National Security Agency — agreed that the Russian government, directed by President Vladimir Putin, meddled in the 2016 election to try to undermine faith in US democracy and hurt Clinton's candidacy.

The US Intelligence Community, made up of more than a dozen agencies, also issued a statement in October concluding that the Russian government directed the election interference.

Trump also argued that intelligence agencies had made "mistakes," and he referred to the faulty conclusion that Iraq possessed weapons of mass destruction following the 9/11 attacks — information that bolstered President George W. Bush's decision to invade the country in 2003.

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