Russia turns toxic for Trump
White House can no longer afford to be seen as soft on Moscow
It was not long ago that Mr Michael Flynn, who resigned as US National Security Adviser on Monday night, was seen as giving then struggling presidential candidate Donald Trump some much-needed legitimacy.
Gone after 24 days in his role, Mr Flynn is the victim of his own mistakes - not least being less-than-truthful to senior administration officials, including the Vice-President, about what he had said to the Russian ambassador shortly before Mr Trump's inauguration.
It is still early days for Mr Trump. But more than any other story so far, Mr Flynn's saga tells us some important things.
Those in Washington and beyond, particularly in Moscow, should take notice - for Mr Trump, Russia is now toxic.
If there was ever a secret conspiracy between Russian President Vladimir Putin and Mr Donald Trump - or even just those around him - to shape events in Washington, it has already run off the rails.
Few people believe that anything Russia might have done - even hacking the Democratic National Party e-mails - was enough to swing the election in Mr Trump's favour.
But the suggestion of an improper link is now ubiquitous, and it is not going away.
The truth may matter less than perception.
Mr Flynn's conversations with the Russian ambassador, prior to Mr Trump's inauguration, were unorthodox.
His business dealings in Moscow also fuelled rumours that, even more so than the President, Mr Flynn was somehow "compromised".
But given the lingering suspicions surrounding Mr Trump's relationship with Mr Putin, the Trump administration cannot afford to look "weak" - and certainly not manipulated - on anything to do with Russia.
For the Trump White House, no one is untouchable. Except perhaps the President.
Mr Flynn was always a controversial figure, and his endorsement of the Trump campaign hardly made him less so.
Even at the Defense Intelligence Agency, he had many detractors, including those who accused him of making up "Flynn facts" to support his arguments when he needed them.
But for all his enemies, he still had fans within the intelligence and security community and beyond.
In the White House, Mr Flynn was eclipsed almost immediately by Defense Secretary and former Marine James "Mad Dog" Mattis.
An asset during the campaign, Mr Flynn became almost immediately a liability.
It is a lesson others in the administration, from White House Press Secretary Sean Spicer to figures more ensconced, such as chief strategist Stephen Bannon or Chief of Staff Reince Priebus, should consider.
The Trump White House could become a Game of Thrones-style political bloodbath. At the very least, everyone is leaking.
And it seems unlikely to stop.
Mr Priebus may be next in line for the chop, with a Trump family friend, Mr Christopher Ruddy, telling journalists this weekend that the Chief of Staff was in "way over his head" and should be removed.
More broadly, political appointees and career government officials alike appear to be leaking a colossal number of insights and snippets of gossip to the media, particularly the New York Times, Washington Post and Politico.
The result is a portrayal of a White House in chaos, where no one can figure out how to turn on the lights, the President is unpredictable and isolated, and everyone is at each other's throats.
It is probably an exaggeration, but it must be infuriating, for Mr Trump in particular, and may become a self-fulfilling prophecy.
What Mr Flynn has demonstrated is that there are limits to what you can get away with.
Misleading the Vice-President or other senior officials can be fatal.
The President can get away with more than anyone else - not least because he is so difficult to remove - but even he might struggle if found to have lied to Congress or the American people on something important. - REUTERS
Peter Apps is Reuters global affairs columnist, writing on international affairs, globalisation, conflict and other issues. He is founder and executive director of the Project for Study of the 21st Century; PS21, a non-national, non-partisan, non-ideological think tank in London, New York and Washington. Since 2016, he has been a member of the British Army Reserve and the UK Labour Party.