The threat arrived before dawn.
From his glimmering Manhattan tower, President-elect Donald Trump launched a 7:30 a.m. missive to his 18.9 million Twitter followers: "General Motors is sending Mexican made model of Chevy Cruze to U.S. car dealers-tax free across border. Make in U.S.A. or pay big border tax!"
Trump's demand ricocheted across social media in some 18,000 retweets. Then came the fallout: Google searches about GM spiked by 200 percent. GM's stock value declined by 24 cents to $34.60 a share. And at corporate headquarters in Detroit, GM executives sprang into action. They had a reputation to save - and facts to correct.
At 9:10 a.m. landed a statement from one of the world's biggest corporations: "All Chevrolet Cruze sedans sold in the U.S. are built in GM's assembly plant in Lordstown, Ohio." The automaker added that it assembles a hatchback Cruze model in Mexico but that it is for "global markets"and that only 4,500, or about 2 percent, were sold on American soil.
This was Tuesday morning. By week's end, Trump had jolted the news cycle again and again with the social-media version of a SkyMall catalogue: something for everything.
There was the tweet shaming House Republicans for trying to gut an independent ethics office, the one promoting inauguration singer Jackie Evancho, the one ripping Toyota for making Corollas in Mexico, the one tormenting Arnold Schwarzenegger for poor ratings on "The Celebrity Apprentice," and more.
The president-elect's targets responded, scrapped plans and, in the case of Schwarzenegger, countered with a Lincolnesque appeal to "the better angels of our nature."
Prolific, indiscriminate and often deceptive tweeting has been a central part of Trump's public identity for years, well before he ran for president. He long ago mastered the medium to promote his brand, deflect unwanted attention and settle scores.
During the campaign, Trump used Twitter to insult his adversaries and punch at people he thought had slighted him, such as former Mexican president Vicente Fox. (Fox, in turn, regularly hits back at Trump on Twitter.)
But now, two weeks before being sworn in as president, Trump's megaphone - technically, an Android device on which he pecks out pithy bulletins - has consequences that go far beyond a "there-he-goes-again"dismissal. He is about to be the president, moving markets and taking action.
On Saturday, Trump used Twitter to argue again that Russia's hacking during last year's presidential campaign had no bearing on his victory, despite a report from U.S. intelligence agencies concluding that the Russian strategy was to boost Trump's chances.
He also tweeted that having "a good relationship with Russia is a good thing, not a bad thing."
Trump's communications approach has left corporate executives, celebrities, politicians, foreign diplomats and national security brass apprehensive about what he might pop off about - and when.
"It's a fascinating real-time live test of how companies act when they're under temporary duress at the hands of the most powerful person in the world," said Ari Fleischer, a former White House press secretary who now advises companies and other organisations on crisis communications.
Fleischer said corporations face a choice: "Cave immediately"to meet Trump's demands or "think long-term and recognise that the moment of duress will pass, that another tweet will be tweeted."
Corey Lewandowski, Trump's former campaign manager, called Twitter "a very, very powerful weapon"for the president-elect.
"Donald Trump's Twitter account is the greatest bully pulpit that has ever existed," he said. "In 140 characters, he can change the direction of a Fortune 100 company, he can notify world leaders and he can also notify government agencies that business as usual is over."
Trump's use of Twitter - which aides have said he plans to continue in the White House - has unnerved foreign governments. In China, for instance, the state-run media recently admonished Trump for a "Twitter foreign policy"that amounts to "child's play." South Korea's Ministry of Foreign Affairs recently assigned an officer in its North American bureau to monitor Trump's Twitter account, the Korea Joongang Daily reported.
Top aides are also left to wonder what Trump might tweet. Each morning when Sean Spicer wakes up, the incoming White House press secretary immediately checks Twitter to see what his boss has said.
"I do look there first, because that's what's going to drive the news," Spicer said Wednesday night at the University of Chicago's Institute of Politics.
Most politicians rely on a committee of advisers to help them craft their tweets, but not Trump. "I do not get a memo," Spicer said of the president-elect's tweets. "He drives the train on this."
For Trump, his online dominance is a source of pride. He boasts to friends, aides and journalists alike about the quality of his writing - pointed, pungent and memorable - and claims that people call him "the Ernest Hemingway of Twitter."
In what one could argue is a sign of his authenticity - or of his carelessness - Trump misspells words with regularity. In December, for instance, he tweeted that China's seizure of a U.S. Navy drone was "an unpresidented act." He was mocked and ended up deleting the tweet and sending a new one with the proper spelling of "unprecedented."
The president-elect's prime time is morning, sometimes as early as 6 a.m., when he is typically in his penthouse apartment at Trump Tower flipping through the tabloids and monitoring cable news shows such as MSNBC's "Morning Joe."
Trump often reacts to stories that catch his eye, as was the case Tuesday morning, when he went after Republicans in Congress for considering changing House rules that would gut an independent ethics watchdog.
The siren blared at 10:03 a.m. in a pair of tweets: "With all that Congress has to work on, do they really have to make the weakening of the Independent Ethics Watchdog, as unfair as it . . . may be, their number one act and priority. Focus on tax reform, healthcare and so many other things of far greater importance! #DTS"
The hashtag stood for "drain the swamp," a Trump campaign mantra. House Republicans had voted preliminarily Monday night to amend House rules to significantly weaken the independent Office of Congressional Ethics.
By 11 a.m., House Speaker Paul Ryan, R-Wis., was huddled in his office with fellow GOP leaders to craft a plan. By then, House members had been besieged with angry calls from constituents. House Majority Leader Kevin McCarthy, R-Calif., told the group there would not be enough votes on the floor to pass the changes.
Within an hour, social media lit up. Trump's tweets were retweeted a combined 21 million times. Google searches about House ethics quadrupled from the morning.
At noon, House Republicans met privately in the Capitol basement and scrapped their plans. The push was over. Trump achieved a victory, of sorts. House members said Trump's tweets were not the driving force but a key factor nonetheless.
"He was mentioned in the room," Rep. Charlie Dent, R-Pa., said. "They said the president-elect is opposed to this action and that should be a consideration."
Trump's tweets are not all provocations or demands. His digital library has many genres. He often opines about American culture, with the kind of wistfulness befitting a septuagenarian son of the New York borough of Queens. And Trump is quick to take credit for popular trends.
Enter Jackie Evancho, a little-known 16-year-old singer whose biggest claim to fame until now is having been a contestant on "America's Got Talent," a reality television show. She was selected to sing the national anthem at Trump's Jan. 20 inauguration, following in the footsteps of Beyoncé in 2013 and Aretha Franklin in 2009 (Franklin sang "My Country Tis of Thee").
On Wednesday, Trump took a pause during a day of transition meetings to chime in on Evancho.
"Jackie Evancho's album sales have skyrocketed after announcing her Inauguration performance. Some people just don't understand the 'Movement,' "Trump tweeted at 1:52 p.m.
Almost immediately, far away in Los Angeles, Kim Jakwerth's cellphone started buzzing - and it didn't seem to stop for hours. Jakwerth is Evancho's publicist, and reporters were calling trying to fact-check Trump's claim that Evancho's record sales had soared.
"I'm getting a million calls. Everybody's calling to ask, 'Is it true?' "Jakwerth said.
In fact, Evancho's sales have risen since the Dec. 14 announcement that she will sing at the inauguration. But the reason is unclear. Her latest album, "Someday at Christmas," is holiday music, the sales of which typically spike in December.
During the week ending Dec. 15, she sold 7,206 copies, the Associated Press reported, citing data from Nielsen Music. The following week, ending Dec. 22, she sold 18,788 copies. The next week, ending Dec. 29, she sold 11,096 copies.
For context, the top-selling album during those weeks was Pentatonix's "A Pentatonix Christmas." During the weeks ending Dec. 22 and Dec. 29, the pop group sold 206,000 and 101,000 albums, respectively.
Jakwerth defended her client: "People are being nasty about it. She's a classical crossover artist. You can't compare it to Beyoncé. . . . You can't compare it to Pentatonix, which is a huge pop group." Jakwerth described Evancho as a classicist who can cross over into pop, "like Céline [Dion] and Adele, in that big beautiful voice - not Britney Spears pop."
The publicist credited Trump with generating mass-market interest in Evancho.
"There has not been a network that has not contacted me - I'm talking from Fox to ABC to CBS - asking to talk to her," Jakwerth said, noting that Evancho will appear on many shows in the run-up to the inauguration. "It's like, 'How come when she had a Christmas record and I tried to book her you didn't want to book her and now you do?' "
Car companies in the firing line
After getting the attention of GM on Tuesday by threatening an import tax on the Cruze, Trump decided Thursday to shift his focus to another automotive giant: Toyota.
In a 1:14 p.m. tweet, the president-elect wrote: "Toyota Motor said will build a new plant in Baja, Mexico, to build Corolla cars for U.S. NO WAY! Build plant in U.S. or pay big border tax."
Within two hours, the company issued a response - and a correction of Trump. Toyota, which is based in Japan, explained that its plant in Baja is 14 years old and actually supports production for a U.S. plant, in San Antonio, which last year built about 230,000 Tundras and Tacomas.
The statement went on to say that Toyota is opening a Corolla plant in Mexico - emphasizing in bold text that it is earmarked for Guanajuato, as opposed to Baja - and that "production volume or employment in the U.S. will not decrease as a result of our new plant."
The company also defended itself on Twitter with figures. Over the past three years, the automaker said, it has invested $700 million in U.S. manufacturing, creating 1,130 jobs in Kentucky, Indiana and West Virginia.
That was not enough to erase the damage of Trump's missive. Toyota's stock price had fallen to $120.44 from $121.08 when New York markets closed Thursday afternoon.
Meanwhile, in Japan on Friday, the government's chief cabinet secretary, Yoshihide Suga, came to Toyota's defense, calling the company an "important corporate citizen."
But by Friday morning in New York, markets opened with Toyota's stock price having fallen further, to $119.84.
Trump takes on Arnie
The classic Trump tweet is one that combines a biting insult of a rival with a reminder of Trump's dominance. One clear example came Friday with a dispatch about Arnold Schwarzenegger, Trump's successor on "The Celebrity Apprentice," NBC's hit reality television series in which Trump still holds a financial interest as executive producer.
Trump's pair of tweets began at 7:34 a.m.: "Wow, the ratings are in and Arnold Schwarzenegger got 'swamped' (or destroyed) by comparison to the ratings machine, DJT. So much for . . . being a movie star-and that was season 1 compared to season 14. Now compare him to my season 1. But who cares, he supported Kasich & Hillary."
Indeed, Monday's debut of the heavily promoted "The New Celebrity Apprentice"- starring Schwarzenegger, a veteran film star and former California governor - attracted 4.9 million viewers, according to Nielsen. That was down more than 22 percent from the debut episode in 2014, Trump's most recent season hosting the program.
When Trump tweeted, Schwarzenegger was fast asleep at his home in Brentwood, Calif. The moment Schwarzenegger woke up, around 6 a.m. Pacific time, he knew he had an issue. He quickly gathered a few advisers on a FaceTime conference call.
"Arnold wanted to respond in a way that was befitting of a former governor," aide Daniel Ketchell said.
Schwarzenegger recalled a video he recorded on last year's Election Day in his study at home, and released the day after, quoting president Abraham Lincoln.
"I'm sure you want to hear me read Lincoln's speeches in my Austrian accent," Schwarzenegger says playfully. Quoting Lincoln, he adds, "We are not enemies, but friends. . . . Though passion may have strained it must not break our bonds of affection. . . . the better angels of our nature."
At 10:05 a.m. Eastern on Friday, Schwarzenegger tweeted the same video and wrote: "Please study this quote from Lincoln's inaugural, @realDonaldTrump. It inspired me every day I was Governor, and I hope it inspires you."
Ketchell described Schwarzenegger's mind-set: "It was very much a quick, OK, I want to keep my governor-type attitude of bringing people together. I'm putting it out."
The Washington Post's Robert Costa contributed to this report.