He imposed tariffs on steel and aluminum imports from a host of nations, saying it was necessary to force changes in other countries' trade practices. He threatened to rip up the North American Free Trade Agreement if Canada and Mexico didn't agree to a new trade deal, a move that could have crippled both of their economies.
He said he would withdraw the United States from the North Atlantic Treaty Organisation if other countries didn't spend more money on their militaries, a move that eventually helped pave the way for the departure of Defence Secretary Jim Mattis.
It is a well-worn tactic from Trump's business career, but this is the first time the livelihoods of so many US workers and households have hung in the balance as a result of it.
"It's a Trumpian way of negotiating," long-time friend Larry Kudlow told a radio interviewer last year before joining the White House. "You knock them in the teeth and get their attention. And then you kind of work out a deal."
But there is mounting evidence that the firm resistance from Democrats is forcing Trump to take his threats much further than he thought necessary.
There are signs the lengthy shutdown is starting to damage the US economy, as consumer confidence has fallen to its lowest level of Trump's presidency, and a growing number of federal workers is expressing exasperation at being required to continue working without pay.
Many have visited food banks and are accepting free meals, while others have begun selling possessions online and are bracing for mortgage payments due next week.
Trump's strategy of using such a large segment of the US workforce as leverage has never before been used on such a scale. Presidents typically rely on the federal workforce to keep the government open, seeking to protect them from partisan fights. But Trump has told advisers he thinks the shutdown gives him the leverage he needs to force the appropriation of money to build a wall along the US-Mexico border. He thinks Democrats will back down before he is forced to.
"With a powerful Wall or Steel Barrier, Crime Rates (and Drugs) will go substantially down all over the US," Trump wrote on Twitter today. "The Dems know this but want to play political games. Must finally be done correctly. No Cave!"
The White House did not respond to requests for comment.
In the early months of his administration, Trump repeatedly told top aides, including then-National Economic Council Director Gary Cohn, that imposing tariffs on imports was a way to create leverage and force other leaders to make concessions.
Cohn would argue that tariffs imposed on US allies actually made it harder for the White House to build an alliance to counter China, according to people familiar with the matter.
Trump also insisted that he would pull US troops off the Korean Peninsula if South Korea didn't agree to modify a trade deal to make it better for the United States.
Trump often talks about leverage and power in private meetings with aides. He has said he uses these tactics to make sure "everyone else has to come to the table," according to a person who has heard his comments.
"He's not afraid to make any threat," this person said. "He assumes everyone else is thinking like he is."
In the early days of the shutdown, the President grew frustrated with Senate Majority Leader Mitch McConnell and then-House Speaker Paul Ryan, and told them they misunderstood what a strong bargaining position he was in. Initially, McConnell and Ryan tried to persuade Trump not to shut down parts of the government and instead support a bill that would fund agency operations.
"Trump is running the shutdown as a reality television producer," said Dan Eberhart, a prominent Republican donor. "The problem is he was hired to run a government, grow an economy and protect a country, not be a successful producer."
One foreign diplomat said the US President at first unnerved European leaders and scared them with his rhetoric. "Now you just know what he's going to do and you kind of shrug it off. You can't totally ignore him because he's the President of the United States. But he doesn't scare people like he used to."
"All of life is a negotiation, and that every negotiation is a zero-sum game," former Trump aide Cliff Sims writes in his new book, Team of Vipers, describing Trump's outlook. "There's no such thing as a win-win; someone will win, and someone will lose."
Trump did not initially plan on forcing the government shutdown. McConnell and Ryan thought they had persuaded him to sign a government spending bill that did not include money for a border wall just days before government agencies would run out of money.
But he reversed course two days before funding was scheduled to lapse, under pressure from conservative activists, and decided to employ his leverage strategy for the first time with Congress. Several White House officials said there was no plan for what to do next, and they had to come up with a plan after the shutdown began.
"This guy is not really good at thinking his way out of the problem," said Timothy Naftali, a clinical associate professor of public service at New York University. "He just ups the ante and hopes the pain he causes others pushes them beyond their pain threshold."
Trump has followed the same script at least eight times before. He threatened to withdraw from Nafta if Canada and Mexico did not agree to major changes. This prompted a forceful retort from Canadian Prime Minister Justin Trudeau.
"We're polite, we're reasonable, but we also will not be pushed around," Trudeau said in June.
Trump threatened to impose tariffs on all automotive imports from Europe unless European leaders dropped tariffs on US-produced cars.
"We won't talk at all with a country if it is with a gun to our heads," French President Emmanuel Macron said in March.
Trump has used the tactic most often with China, slapping duties on US$250 billion of goods imported from China and threatening to go even further if China does not agree to major changes in the way it trades with the United States.
"How could you negotiate with someone when he puts a knife on your neck?" China's deputy trade negotiator, Wang Shouwen, said at a news conference in September.
Trump has embraced this tough-guy persona. During a news conference last year, he told a Japanese reporter, "Say hello to Shinzo," referring to Japan's Prime Minister, Shinzo Abe. "I'm sure he's happy about tariffs on his cars."
Trump has not moved to impose tariffs on Japanese cars, but he has continued threatening to do it unless Japan makes it easier for US cars to be sold in Japan.
In many of these cases, Trump's hardball tactics ultimately have brought the foreign counterparts to the negotiating table, though whether they will prove effective is unclear.
In many of these cases, Republican lawmakers have grumbled about Trump's tactics but have done little to intervene. The shutdown has caused even more GOP angst, but Republicans have largely followed the President's lead, with a majority saying his latest offer to Democrats is sufficient to win their support.
That proposal would temporarily prevent the deportation of roughly one million young undocumented immigrants, for a period of three years, in exchange for US$5.7 billion in taxpayer money to build sections of a wall on the US-Mexico border.
This offer includes pressure points that Trump himself has created as a way to try to force capitulation from Democrats. It was Trump who moved in the past two years to eliminate the immigration benefits he is now offering to reinstate temporarily. And the shutdown he is offering to end is something he triggered as well.
"Congress says it's hostage taking because they're not the ones controlling the leverage," said Paul Winfree, who was deputy domestic policy adviser at the White House until leaving last year. "Congress has routinely shown that it doesn't legislate unless forced. They create their own set of cliffs and catastrophes to force action."
Lawmakers do tend to wait until the last minute to pass controversial pieces of legislation, which is one reason they didn't avert a shutdown. But Trump's critics think he will use this same tactic again in a few months, when lawmakers must decide whether to raise the debt ceiling or risk having the government default on its debts.
"He can't be successful on holding these folks hostage, because he will do it again on the debt ceiling and the end of the appropriations cycle," Senator Mark Warner, D, said.
Neither Democrats nor Republicans said they felt certain how the shutdown would end and whether Trump would eventually back down. White House officials are also looking for clues, but no resolution appears to be within reach.
"Trump is trying to harness the drama of political theater to get what he wants," Winfree said. "The problem is that once you shake things up, it's difficult to control the outcome."
