US President Donald Trump said that he thinks Russia was behind 2016 election meddling, but added he feels “it could have been other people in other countries” and that “nobody really knows for sure”.

“I think it very well could be Russia but I think it could very well have been other countries,” Trump said on Thursday during a news conference with Polish President Andrzej Duda in which he also slammed the news media, including CNN and NBC. “I think a lot of people interfere.”

Trump, asked about the fact the United States intelligence community has said it was Russia, compared that assessment to the eventually debunked claim that Iraq had weapons of mass destruction in the lead-up to the Iraq War, CNN reported.

“I think it was Russia but I think it was probably other people and or countries. I see nothing wrong with that statement,” Trump said. “Nobody really knows. Nobody really knows for sure.”

He added, “I remember when I was sitting back listening about Iraq, weapons of mass destruction, how everybody was 100 per cent certain that Iraq has weapons of mass destruction. Guess what? That led to one big mess. They were wrong and it led to a mess.”

The intelligence community assessment spans both Obama and Trump administrations, however. Intelligence officials nominated by Trump have publicly said they have no doubt that Russia was behind the election meddling.

Russian meddling in the 2016 election is the subject of numerous investigations in Washington, casting a pall over the White House. The swirl of Russia investigations — and possible connections between Trump’s orbit and Russian officials — has caused friction on Capitol Hill, hampering Trump’s ability to score a number of legislative victories.

Trump slammed former President Barack Obama’s handling of Russian interference as he stood next to Duda, arguing that the former president “did nothing” to combat the interference.

“Why did he do nothing about it? He was told it was Russia by the CIA … and he did nothing about it,” Trump said. “They said he choked. I don’t think he choked. Well, I don’t think he choked. I think what happened was he thought Hillary Clinton was going to win the election and he said let’s not do anything about it. Had he thought the other way, he would have done something about it.”