(CNN) Fifteen months into Donald Trump's presidency, the United States finds itself on the cusp of a grave constitutional emergency at home -- and closer to stumbling into direct conflict with Russia than at any time since the Cold War.

It's a moment when the chaos, wild rhetoric and crushing of presidential norms on which Trump has anchored his presidency could begin to have real-world consequences with constitutional principles and lives on the line.

Washington is reverberating with speculation that Trump, infuriated by revelations emerging from a stunning FBI raid on his personal attorney , could seek to disable or shut down Robert Mueller's special counsel probe.

The rest of the world is braced for an expected strike by the US and its allies against Syria, as Trump taunts Moscow with the prowess of American weaponry and a Kremlin envoy warns that Russia could shoot US missiles down.

The picture of an aggressive President openly mulling an audacious power move to end a lawful probe into his campaign, while deliberately stoking tensions in a dangerous war zone, is one that many of his pre-election critics had feared.

But it's also one that Trump's millions of supporters bought into in 2016.

The President's response opens a window into his character, showing his trust in his own instincts, a desire to project toughness and a refusal to be bound by behavioral constraints observed by his predecessors.

Trump has been fuming ever since FBI agents arrived at the door of his lawyer Michael Cohen on Monday, a move that prompted him to angrily denounce what he said was an "attack on our country."

His fury was unlikely to be ease d by reports Wednesday that the agents were looking for communications between Cohen and him about the infamous "Access Hollywood" tape, which featured vulgar Trump remarks about women.

Even before those revelations, sources told CNN that Trump was already convinced that Mueller, who referred information about Cohen to prosecutors in New York, had busted out of his lane of probing alleged Russian election collusion.

White House spokeswoman Sarah Sanders said Wednesday that the President has "very deep concern about the direction that the special counsel and other investigations have taken."

CNN reported Tuesday that Trump was considering a step many of his opponents fear -- removing Deputy Attorney General Rod Rosenstein, who oversees the Mueller probe, in an attempt to either neuter the special counsel or to dismiss him entirely and end his probe.

"Either of those actions are designed to interfere with an investigation that may implicate the President," House Intelligence Committee ranking member Adam Schiff said on CNN's "The Situation Room."

"That is obstruction of justice .... it deeply worries me because it would throw this country into complete crisis," the California Democrat said.

Democrats would be certain to call for impeachment proceedings in such circumstances, even if Republicans who control the House seem unlikely to agree. Some top GOP senators, however, have warned that firing Mueller would be "suicide" for Trump and would mean the beginning of the end of his presidency.

Shock reverberates from Trump lawyer raid

The Trump era has been packed with shocks and unpredictable turns, but the raid by FBI agents Monday on the personal lawyer of the President of the United States left many people in Washington shaking their heads in disbelief.

It also raised genuine questions about whether it was justified, despite being endorsed by Rosenstein and a judge in New York.

"The attorney-client privilege is sacrosanct here. There is the crime fraud exception -- the only time you get to pierce that attorney-client privilege is if there is a crime committed," said David Urban, a CNN political commentator who ran Trump's 2016 campaign in Pennsylvania.

"This is a pretty high bar stuff and we will have to see, but it is an extraordinary step to be taken, for sure," Urban told Jake Tapper on CNN's "The Lead."

CNN reporting indicates that New York prosecutors were also seeking information about payments made to two women who alleged that they had affairs with Trump a decade before the election.

The prosecutorial strategy was not immediately clear. But Democratic Sen. Richard Blumenthal suggested on CNN that it was possible agents were seeking evidence of obstruction of justice or were seeking to protect evidence.

Backdrop of extraordinary turmoil

The meeting reflected how Trump is preparing to order American forces into action against an extraordinary backdrop of domestic political turmoil.

Concern about the gravity of the potential strikes, to punish an alleged chemical weapons attack on Syrian civilians by President Bashar al-Assad's forces, escalated amid a US-Russia war of words on Wednesday.

After Russia's ambassador in Lebanon warned th at Moscow could shoot down US cruise missiles and retaliate against launch sites -- possibly US ships and submarines -- Trump hit back.

Far from easing tensions with America's nuclear-armed rival, as most presidents may have done, he sent them into overdrive.

"Russia vows to shoot down any and all missiles fired at Syria. Get ready Russia, because they will be coming, nice and new and 'smart!' You shouldn't be partners with a Gas Killing Animal who kills his people and enjoys it!" Trump tweeted.

On the one hand, the tweet could be put down to Trump's unique and unconventional way of communicating, which infuriates the Washington establishment and delights his supporters.

Yet such talk, on the question of military action in a region where American and Russian forces are nudging up against each other, is not the kind of rhetoric that is normal from a president.

"He's the commander in chief. I can't remember ever in my lifetime or certainly in my study of American history a commander in chief treating the potential use of armed force in this cavalier a fashion," said retired Rear Adm. John Kirby, a CNN national security analyst and former State Department spokesman.

"It is irresponsible that he would just tweet out something specific about a strike when lives are at stake, not just lives on the ground, but American lives and probably allied lives," he said.

The tweet is also not consistent with Trump's own oft-stated promise never to tip his hand on the possibility of military action in order to avoid giving regimes like the one in Syria time to move military hardware out of harm's way.

Still, some of Trump's defenders might note the irony of the media, which have spent months wondering why Trump has been soft on Russia, highlighting tough rhetoric directed at the Kremlin over its support of Assad.