The Trump administration suffered its first high-profile casualty after the country's top security official was forced to resign in a controversy that has reignited concern about the US president's ties with Russia.
Retired general Michael Flynn was dismissed by Mr Trump late on Monday night, over his failure to inform top White House officials of the nature of his conversations with the Russian ambassador to the United States during which he discussed sanctions.
But almost immediately the focus turned to Mr Trump’s role in the affair, after it was confirmed that the president had been informed of the matter almost three weeks before he dismissed his top security official.
As national security adviser, Mr Flynn was privy to the highest level of classified information held by the United States and briefed the president on national security matters every morning.
An early supporter of Mr Trump, he accompanied the president to his Florida retreat this weekend and briefed the president as recently as Monday.
In his resignation letter, Mr Flynn – who had previously been dismissed by former US president Barack Obama as head of the defence intelligence agency – admitted he had "inadvertently briefed the vice-president elect and others with incomplete information" about the phone calls.
Crucially, Mr Flynn's discussions with Russian ambassador Sergei Kislyak took place late last year before Mr Trump was elected president, in breach of a US law known as the Logan Act which prohibits private citizens from engaging in diplomacy with any foreign power.
Possible prosecution
There were suggestions last night that Mr Flynn could face prosecution, amid reports that the FBI interviewed him during his first few days as national security adviser.
Leading Democrats have called for an independent investigation into the sudden resignation of Mr Flynn.
In his only public comments on the matter, Mr Trump said on Twitter on Tuesdaythat the “real story” was the leaking of the story to the media.
As the controversy over the extent of Mr Trump’s knowledge of Mr Flynn’s conversation with the Russian ambassador continued, the White House was also drawn into a number of unrelated controversies.
The Republican oversight committee announced it is to seek information regarding reports that Mr Trump shared sensitive information in an unsecured area at his Florida resort, Mar-a-Lago last weekend.
Pictures appeared to show Mr Trump discussing the North Korea missile test with Japanese prime minister Shinzo Abe in an unsecured area of the resort late on Saturday night but the White House has said the two men were discussing other matters at that time.
Meanwhile, the Office of Government Ethics has written to the White House stating that Kellyanne Conway, an adviser to Mr Trump, may have violated the ethics code by encouraging viewers to buy Ivanka Trump's products during an interview on Fox last week.
