The word "shocking" is overused but nobody doubts that the scenes in Washington are shocking:
- Law-makers crouched in fear on the floor of the Senate as armed marauders try to disrupt an essential process of democracy - in the world's leading democracy.
- Shots fired on Capitol Hill
- A hooded "protester" sitting on the rostrum of the Senate where the Chief Justice of the United States on occasion sits.
- Police officers pointing pistols at protestors trying to enter the Capitol, the building containing the two chambers of the American "parliament".
- Washington under curfew.
To call it a coup would be to aggrandize it, but it has the look of attempted takeovers of power by tin-pot generals in Latin American countries in the 1960s and 1970s or of the coup in Spain in 1936.
Indeed, former President George W. Bush said: "This is how election results are disputed in a banana republic."
But it isn't an attempted coup because the military are loyal to the Constitution.
Less than a week ago, all living Secretaries of Defense signed a letter saying: "The time for questioning the results has passed; the time for the formal counting of the electoral college votes, as prescribed in the Constitution and statute, has arrived."
What has Mr Trump said and done
He has not shown any hint of accepting the result of the presidential election which gave the Democrat, Joe Biden, 81,283,485 votes and Mr Trump 74,223,744 - and which gave Mr Biden an overwhelming majority in the electoral college by which presidents are chosen.
Not one of his allegations of fraud at the ballot box has made any progress in dozens of court challenges across the country, often with Republican-appointed judges presiding.
He has turned on former allies who have not endorsed his bogus claims, even Vice President Mike Pence whose role in the current proceedings was merely to rubber-stamp the election result. Mr Trump had wanted him to defy all convention and refuse to play his procedural role.
When Mr Pence declined to do Mr Trump's bidding, the president tweeted: "Mike Pence didn't have the courage to do what should have been done."
This week a recording of a phone call emerged in which Mr Trump urged Georgia's secretary of state, to "find" enough votes to thwart Biden's victory there.
A few days ago, he fired up a crowd in Georgia, the usually staunchly Republican state which switched against him in the presidential election.
At the rally he said: "They're not taking this White House. We're going to fight like hell."
Mr Trump's supporters seem to have taken him at his word. Some of them armed themselves and stormed the Capitol, that iconic confection of a building which is the very symbol of American democracy.
Mr Trump then tweeted a video of himself telling them to "go home".
Will he leave the White House?
He will but it is now just about conceivable that he will have to be escorted out. What was once incredible is now possible.
The Republican Party is in disarray. Just before the storming of the Capitol, the Republican leader of the Senate, Senator Mitch McConnell, finally distanced himself from Mr Trump.
"Nothing before us proves illegality of the massive scale that would have tipped the entire election. Nor can public doubt alone justify a radical break when the doubt was incited without any evidence," the Republican leader in the Senate said.
"This election was not unusually close," he added. "If this election were overturned by the losing side, our democracy would enter a death spiral."
Republican Senator Ben Sasse pointed his finger at Mr Trump as the instigator of the terrible events in Washington: "Today, the United States Capitol - the world's greatest symbol of self-government - was ransacked while the leader of the free world cowered behind his keyboard."
"Lies have consequences," he continued. "This violence was the inevitable and ugly outcome of the president's addiction to constantly stoking division."
But the other wing of the Republican Party - what you might call the ultras - believes that Mr Trump was defrauded and that he will return.
They have a messianic belief in the leader - and many of them will have a say in who the Republican candidate in 2024 will be.
Will Mr Trump be able to run for president in 2024?
As a one-term president, he is entitled to run for a second term.
The 22nd amendment of the US constitution says: "No person shall be elected to the office of the President more than twice".
In four years, he will be 78, only a year older than Mr Biden is now.
But the events of the last week or so may have finally turned more Republicans against him. The party lost both Senate seats in Georgia, a formerly sure-fire Republican state. Mr Trump's intemperate intervention may well have raised the Democratic turnout.
If he were impeached - accused of crime by Congress - and found guilty, he would be barred from running again.
The convention is that former presidents are not pursued after they leave office. In 1974, President Gerald Ford pardoned his predecessor for his part in the crimes committed in the Watergate break-in, reasoning that he didn't want to prolong America's "long national nightmare".
But there are already calls for Mr Trump's impeachment.
"Congress must now act, not just to remove Trump, but to ensure that no president ever risks behaving in this way again," Yoni Appelbaum writes in The Atlantic, a liberal American magazine.
"Impeachment is the constitutional mechanism for holding a president accountable, a defiant emphasis upon the rule of law in the face of mob violence, a reassertion of the primacy of American institutions over the rule of passions."
It would need a simple majority in the House of Representatives for conviction and a two-thirds majority in the Senate.
The latter enhanced majority remains unlikely because of the near 50-50 split in the Senate - after the Georgia results, the Democrats look like having a majority by a sliver.
It would also be very, very divisive.
It is highly unlikely to happen - but then so was a president defying an electorate and his followers storming the seat of government of the United States of America.
- Live updates on Capitol siege
- Twitter locks Trump, Facebook pulls video
- Trump's rage ignites assault on democracy
- Congress resumes after protest incursion
- More calls for President Trump's removal
- White House staffers resign after violence
- Trump tells protesters 'remember the day'
- Fear as pro-Trump mob occupied Congress
- Obama says Trump incited violence
- Bill Clinton: poison politics behind riots
- Corporate group urges Trump's removal
- UK PM condemns Washington protest
- Evacuations as protesters breach Capitol