The Congressional investigation into the January 6 assault on the US Capitol by a mob loyal to Donald Trump is increasingly focusing on the former president and his top aides -- and what they did before the riot.

Last week, an appeals court ruled that Trump cannot block the release to investigators of his White House records relating to the attack, and his former chief of staff Mark Meadows faces being ruled in contempt for refusing to testify.

The committee has so far interviewed nearly 300 people.

It is piecing together a picture of the moves made by Trump after he lost the November 2020 election to Joe Biden, and the possibility that he was attempting to engineer a coup in an unprecedented threat to US democracy.

Here is a look at what happened in the crucial weeks leading up to January 6, 2021:

Trump serious about reversing election

Trump's pushback against Biden's election victory was not just an extended fit of pique, but rather a serious effort to retain power, which the Republican mounted for weeks.

After failing to reverse vote counts in the states he needed to change the result, Trump focused intensely on preventing Congress from certifying Biden's victory on January 6.

In mid-December, attorney John Eastman laid out for Trump a precise plan to have then vice president Mike Pence, who was to preside over the certification, exploit legal loopholes to keep Biden from moving into the Oval Office.

Meadows was one of several people close to Trump who, according to various reports, disseminated that plan, along with bizarre conspiracy theories alleging the election was fraudulent.

Others in Trump's camp also mapped out legal justifications for Pence to reject Biden's certification.

Pence, increasingly under pressure, sought advice in late December from former vice president Dan Quayle, who said he was required to certify Biden's win.

But according to new accounts and books about Trump's last months in office, Pence simply would not say no to his boss.

"You don't know the position I'm in," he said, according to "Peril," the book by journalists Bob Woodward and Robert Costa.

"There are other guys saying I've got this power."

Meanwhile, on January 5 and 6, Trump, Meadows and other White House aides liaised regularly with a "war room" in a nearby hotel staffed by Eastman, advisor Steve Bannon and numerous others, who also were in contact with Trump supporters in the streets.

CIA, Pentagon feared Trump 'coup'

In the weeks after Trump refused to concede defeat, top officials feared he could try to mobilize the military to hold onto power.

They also feared that Trump, out of frustration, could start a war.

After the election, when Trump fired defense secretary Mark Esper, CIA Director Gina Haspel called the chairman of the Joint Chiefs of Staff, General Mark Milley, saying: "We are on the way to a right-wing coup. The whole thing is insanity," according to "Peril."

As January 6 neared, Milley warned staff of a "Reichstag moment" -- referring to when Nazis seized power after the 1933 torching of the German parliament.

On January 2, 10 former defense secretaries issued an extraordinary statement warning it was dangerous to challenge the election results or use the military to resolve political issues.

War with Iran, China feared

Nine days after the November election, Trump asked advisors about launching air strikes to take out Iran's entire nuclear program. They persuaded him to stand down, but they were unnerved.

"This is a highly dangerous situation. We are going to lash out for his ego?" Haspel asked Milley, according to "Peril."

When the issue was again raised after a barrage of missiles was launched at the US embassy in Baghdad on December 21, officials struggled to contain Trump, according to "Betrayal," a new book by ABC journalist Jonathan Karl.

But a much more serious situation was smoldering: China was worried an unhinged Trump could attack. And the Pentagon worried that Beijing could launch a first strike.

Just before the election, Milley took the unusual step of calling his Chinese counterpart to offer reassurances.

"I want to assure you the American government is stable," Milley told General Li Zuocheng. "We are not going to attack or conduct any kinetic operations against you."

Beijing's worries resurfaced after the January 6 riot, and Milley called Li again.

"Things may look unsteady.... But that's the nature of democracy, General Li. We are 100 percent steady," he said.

'Got it?'

Before the January 6 attack, the people who might have been able to deter Trump -- the top Republicans in Congress, Senator Mitch McConnell and Congressman Kevin McCarthy -- are depicted in the books as frozen by their own political ambitions, and thus unwilling to challenge Trump.

In the hours after the attack, both Republican and Democratic political figures, including some in Trump's own cabinet, felt he was unstable and should be removed from office by constitutional means.

But there was no clear path, especially as Pence refused to consider it and his support would have been necessary.

Ultimately, Pence certified the election result, and calm was restored -- more or less.

House Speaker Nancy Pelosi called Milley to ask how an "unhinged president" could be prevented from ordering a nuclear strike.

"The nuclear triggers are secure," Milley told her, according to "Peril." "I can assure you that that will not happen."

Milley then called in some senior officers and told them any order coming from Trump had to be checked with him.

He looked at each one and said, "Got it?"