As a candidate, Donald Trump boasted of his lack of government experience and argued his business background qualified him to handle a president's most august responsibility — handling the nuclear arsenal.
On Sunday, hours after North Korea claimed it had tested its first hydrogen bomb, far more powerful than its previous nuclear tests, Defense Secretary James N. Mattis emerged from a meeting that Trump had just held with his top national security advisors, and raised the specter of nuclear war.
Standing in the White House driveway with Gen. Joseph F. Dunford, chairman of the Joint Chiefs of Staff, Mattis warned Pyongyang that aggression against the United States or its allies would trigger a unified world response and what he termed the "total annihilation of a country, namely North Korea."
"Any threat to the United States or its territory, including Guam, or our allies, will be met with a massive military response, a response both effective and overwhelming," Mattis said.
The warning was all the more severe because it came from Mattis, a retired Marine Corps general who had sought to tamp down so many of Trump's bellicose comments and tweets in recent weeks that he was forced to deny a split with the president.
Sunday's drama represented a new reality for Trump. His presidency has been defined largely by political crises of his own making, from his decision to fire FBI Director James B. Comey to his comments after racial violence in Charlottesville, Va. It was inevitable that circumstances outside his reach would complicate his tenure.
And now they have, raising the question of how he will handle a double-barreled pair of crises — the growing threat from North Korea and the recovery and relief efforts for hundreds of thousands of Americans caught in epic floods in Texas and Louisiana.
To add to his challenges, the White House has said Trump will disclose Tuesday whether he will authorize the deportation of 800,000 so-called Dreamers, immigrants brought here illegally as children — a decision that will be politically combustible no matter what he decides.
Off in the wings are high-stakes battles that will begin Tuesday on Capitol Hill, including funding the government to avoid a shutdown by Sept. 30, raising the federal debt ceiling, and approving billions in aid for the victims of Hurricane Harvey's devastation.
Undergirding all these is special counsel Robert S. Mueller III's investigation of whether Trump's aides cooperated with Russian meddling in the 2016 presidential election. That probe has steadily gathered steam, even if pushed out of view in recent weeks.
The combination would tax any president, but particularly Trump, who has proved to be a tempestuous and unpredictable chief executive. And Sunday's events showed again his difficulty in gaining traction for his presidency.
Early this year, Trump's well-received address to Congress was buried within a day by negative developments in the Russian investigation. On Sunday, when he might have been basking in praise from Harvey victims he visited Saturday in Texas and Louisiana, he was instead overtaken by actions half a world away.
The abrupt change of focus from domestic recovery to international fear over North Korean leader Kim Jong Un's growing military might was clear Sunday morning in raw juxtaposition.
Trump and his wife, Melania, attended services in St. John's Church, across Lafayette Park from the White House, to underscore his call for a day of prayer for the benefit of Harvey victims.
As he left, reporters shouted a question: Did he plan to attack North Korea?
"We'll see," he said, and returned to the White House to meet with his top national security advisors.
The confluence of crises hit Washington at the opening of a month already overwhelmed with challenges.
After Congress returns from vacation on Tuesday, lawmakers and the White House face a series of must-do items that have proved volatile and divisive in the past.
As September dawned, relations between the Republican-led White House and Congress remained raw from fallout of the failed effort to repeal and replace Obamacare, which Trump still would like to add to the fall agenda.
The multiple crises hit Trump as he languishes at the low end of polling for most presidents, a fact that limits both his opportunities for persuasion and his ability to threaten.
In a recent Fox News poll, 41% of Americans approved of the way he was conducting his presidency; about the same number, 43%, backed how he had handled the North Korea threat.
Were Trump to help engineer a smooth recovery from Harvey, his image could certainly benefit. But North Korea presents few good options for any president, and Trump's all-over-the-mat response so far has only fueled concerns that he is not up to the task.
Last month, he took two very different positions based largely on the same facts. In early August, he warned Kim against "any more threats" to the United States. Were any to occur, he warned, "they will be met with fire and fury like the world has never seen."
Two weeks later, at a campaign rally in Phoenix, he praised Kim.
"I respect the fact that I believe he is starting to respect us. I respect that fact very much. Respect that fact," he said. "And maybe — probably not — but maybe something positive can come about."
On Sunday, less than two weeks later, he was back to suggesting that the only solution was a military attack.
"South Korea is finding, as I have told them, that their talk of appeasement with North Korea will not work, they only understand one thing!" he tweeted Sunday morning. Trump has added to the uncertainty over his approach by simultaneously threatening a free trade agreement with South Korea, the ally most at risk from the North's belligerence.
Republicans on Sunday were supportive of the president but mindful of the limitations of his presidency. Several referred to the competency of his national security team, seen as a bulwark against the president himself.
Sen. Bob Corker of Tennessee, chairman of the Foreign Relations Committee, spoke in words both carefully crafted and suggestive of a lack of certainty about the president's next moves.
"We stand ready to work with the administration to support a comprehensive strategy that not only places an emphasis on deterrence but also empowers our allies and partners in the region, who must do far more to confront this threat," Corker said in a statement.
More blunt was Arizona Sen. Jeff Flake, like Corker a Republican who has earned the president's enmity for recent remarks critical of his presidency.
Asked by CNN anchor Dana Bash about his confidence in the administration, he repeatedly cited Trump's national security team.
"I'm confident that the people around the president are giving him good advice, and I believe that he will follow it," Flake said. "I sure hope he does. Obviously, you like a leader that's measured and sober and consistent. Our allies want to hear that. I think our adversaries need to hear that."
Asked directly whether he was concerned about Trump himself, Flake replied: "I have had my concerns."
Texas Sen. Ted Cruz similarly disagreed with Trump's tenor — specifically his threat of "fire and fury" against North Korea. But he spun that as a positive.
"The president speaks in ways that I wouldn't speak but that is his prerogative," he said. "I do think it helps for North Korea and for China to understand that we have a president who is strong."
The question is whether a performance evincing strength — or other attributes — will be necessary in the battles ahead.
The North Korea crisis calls for nuance and deliberateness. The Harvey recovery effort will be measured in years, requiring a willingness to dig in for the long haul. Trump's Tuesday announcement on the fate of children brought to this country without proper papers will require top-notch political instincts.
The host of issues looming on Capitol Hill will require mutual respect and policy acumen and a deft hand at managing competing power groups.
So far, Trump largely has favored displays of strength and reveled in unilateral decision-making. The attributes he will now need remain sheathed, if they exist at all.