Trump also lashed out in the morning on Twitter at the news that the Justice Department appointed a special prosecutor, former FBI director Robert Mueller, to oversee the investigation, calling the move a politically motivated "witch hunt" by his Democratic rivals.
The president's comments come as he deals with backlash from firing Comey last week and subsequent reports that raised questions about whether he might have tried to interfere with an investigation.
Mr Trump on Thursday piled onto his mounting reasons for firing Mr Comey, mentioning his "very poor performance" at a recent Senate hearing, and the FBI's declining reputation.
Flynn, who failed to disclose that he spoke with Russian Federation regarding sanctions while Obama was still in office, is a key component in multiple investigations into the Trump campaign's relationship with one of the nation's greatest adversaries.
President Donald Trump continued to criticize a decision by the Justice Department to appoint former FBI Director Robert Mueller as a special counsel in the agency's investigation into Russian Federation on Thursday, saying "it hurts this country terribly".
Lavrov says media reported that Trump told him "terrorists are capable of stuffing laptops, all kinds of electronic devices, with untraceable explosive materials", information he says the administration revealed with the laptop ban. Later, though, Trump told NBC News that he would have fired Comey "regardless" and was thinking of the "Russia thing" when he did so.More news: Emmanuel Macron's first non-Europe trip focuses on fighting extremism
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Trump also contended that Comey "was very unpopular with most people" in Washington - Republicans and Democrats.
"I thought it [Comey firing] would be a bipartisan decision", Trump said, citing Democrats who had called for his ousting.
Trump said later, however, that he had been thinking about "this Russian Federation thing" when he fired Comey, whom he called a "showboat" and a "grandstander" in an interview with NBC's Lester Holt last Thursday. "And everybody, even my enemies, have said there is no collusion", he said.
The appointment of Mueller as special counsel will raise the intensity of the investigation and make it less vulnerable to political interference. There is a belief in this country that no one is above the law. He said Washington needs to get back to issues like creating jobs, health care - saying "we don't have health care in this country" - and his broad outline of a tax cut plan, which he promised would, if passed, be the "biggest tax cut in the history of our nation". Trump repeated that he felt the probe was akin to a "witch hunt" during the Thursday press conference. "I think it divides the country, I think we have a very divided country because of that many other things".
Trump said his administration was committed to cutting the flow of drugs into the United States.
"Walls work. Just as Israel", Trump said, apparently referring to its West Bank barrier.