For many the telling moment came on Friday.
As he entered the east room of the White House to hear US president Donald Trump's joint press remarks with Japanese prime minister Shinzo Abe, vice president Mike Pence paused briefly to shake hands with national security advisor Michael Flynn.
The handshake was cursory, intimating tensions between the two men.
Hours earlier contradictory accounts of a phone call between retired general Flynn and the Russian ambassador to the United States, Sergei Kislyak, had emerged with Flynn rowing back from previous suggestions that he had not discussed sanctions against Russia with the ambassador during the phonecall.
The call took place prior to Trump’s unauguration as president.
On Sunday, senior Trump adviser Stephen Miller, sent out to represent the White House in a series of Sunday morning media interviews, failed to back Flynn when pressed, instead sidestepping questions. The following day Trump's press secretary Sean Spicer said th president was "evaluating" the situation.
With rumours now swirling about Flynn's position, reports emerged late on Monday night that former acting attorney general Sally Yates – the Obama nominee who was fired by Trump for opposing his executive order on immigration – had warned the White House in late January that Flynn may have misled senior administration officials about the nature of his phonecall with the ambassador, and could be vulnerable to Russian blackmail.
Just before midnight on Monday Flynn resigned, stating in his resignation letter that he had “inadvertently” misled administration officials .
The resignation has stunned Washington and marks the first high-profile departure from Trump’s senior team. To be dismissed by one US president may be described as misfortune – Flynn was fired by Barack Obama as head of the defence intelligence agency – but to lose the support of a second suggests something more.
Volatile temperament
Flynn was always one of Trump's riskiest picks for cabinet – the widely-circulated picture of him sitting alongside Russian president Vladimir Putin at a dinner in Moscow in 2015 has dogged him since his appointment, while his reported volatile temperament and strong views on radical Islam made him a controversial pick for national security adviser, despite his reputation for tactical brilliance as a general.
His resignation has sparked questions about how much Trump knew about the phone call with the Russian ambassador and the rival centres of power within the Trump administration.
While Flynn’s undermining of Pence is believed to have sealed his demise – the vice president had said in a series of televised interviews that Flynn had not discussed sanctions in that phonecall – Flynn’s relationship with Trump has also come into the spotlight.
It remains unclear how much Mr Trump knew about the controversy. Was Flynn acting on orders when he discussed the issue of sanctions with the Russian ambassador? Did the White House counsel, when advised by Sally Yates about concerns, pass that information to the president? If not, why did the White House wait two weeks to act on Yates’s warnings? While Flynn technically resigned, was he dismissed by a man who has built his TV persona around his willingness to fire people?
Amid concerns about the leadership style of Trump, focus is now turning to other members of his administration who may be next in the firing line.
One of the intriguing sub-plots of the Flynn controversy is that Trump adviser Kellyanne Conway said on Monday that Flynn had the "full confidence" of the president, but this was contradicted an hour later by press secretary Sean Spicer , who said Trump was "evaluating" the situation.
Rumours about Spicer's own future have also intensified in recent days amid speculation that Trump is not entirely happy with his performance, while there have been unverified reports of clashes between White House chief of staff Reince Priebus and senior advisor Steve Bannon.
Arguably more seriously, however, is the renewed focus now on the US administration’s stance on Russia. With the circumstances surrounding Flynn’s resignation and the motives behind his conversation with the Russian ambassador still unknown, Trump’s relationship with Russia is again in the spotlight.
Admiration for Putin
Flynn was not the only Trump nominee with links to Moscow; secretary of state Rex Tillerson had extensive business interests there as chief executive of Exxon Mobil, which lobbied against US sanctions on Russia.
Trump himself has publicly stated his admiration for Putin, who many, even in his own party, still see as a US foe. A dossier presented to Trump by the CIA last month containing allegations about his links to Russia and behaviour on a trip clouded the early days of Trump’s presidency.
As Trump’s considers a replacement for Flynn, the retired general’s brief spell as national security adviser may be relegated to the history books. But scrutiny of Trump’s relationship with Moscow is only beginning.