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United States President Donald Trump had known that his former National Security Adviser Michael Flynn had not been truthful about his phone call with the Russian ambassador to the US, the White House said in a statement. It also said that Trump only asked him to resign on Monday after it was clear that Flynn had lost his and the Vice President Mike Pence's trust.

Donald Trump's national security adviser Michael Flynn resigns over Russia links

Flynn had made a phone call in late December to the Russian Ambassador Sergey I Kislya, soon after the Obama administration had imposed new sanctions on Russia for interfering with the US elections. He had initially said that the duo had just discussed scheduling matters and the sanction's against Russia were not discussed. Trump affiliates, including Pence, had backed Flynn's claims.

"The evolving and eroding level of trust as a result of this situation is what led the president to ask for General Flynn's resignation," White House press secretary Sean Spicer told reporters at his daily briefing. Spicer for the first time clarified that it was Trump who had fired the senior aide, contrary to earlier reports that Flynn had resigned voluntarily from his position.

There could be more trouble for Flynn ahead as he is reported to not have been completely forthright when the Federal Bureau of Investigation (FBI) agents had interviewed him about his call, the concealing of crucial information could land him in legal problems. Flynn however later had admitted to providing "incomplete information" and not lying about the phone call.

Senate Republican leader Mitch McConnell has suggested that it is "highly likely"  that the intelligence committee of the chamber could investigate the incident as part of its larger investigation of alleged Russian interference in the 2016 US presidential elections, according to Reuters reports.

"We got to a point not based on a legal issue, but based on a trust issue, with the level of trust between the president and General Flynn had eroded to the point where he felt he had to make a change," Spicer said. "The president was very concerned that General Flynn had misled the vice president and others."

Reports state that it was later revealed that the call between the two was intercepted by intelligence officials and Fynn had attempted to assuage Russian concerns about the sanctions during the phone conversation. This move is unprecedented for someone who was just a civilian at the time.

The White House on Monday released a statement naming Lt. General Joseph Kellogg as Acting National Security Advisor for the time.