Donald Trump has defended his prolific use of Twitter before and he's showing no signs of easing off ahead of his inauguration later this month.
He criticised car-maker General Motors for producing its Chevy Cruze models in Mexico, threatening to impose a border tax on cars made outside the US.
Cars made south of the border can be imported into the US tax-free under the North American Free Trade Agreement (NAFTA), an agreement Mr Trump says causes the loss of manufacturing jobs.
General Motors released a statement saying only 2,400 of its 190,000 Chevy Cruze cars are produced in the United States.
Donald Trump also tweeted a Fox News report of Ford's decision to cancel its plans for a US$1.6 billion plant in Mexico.
Ford will instead invest US$700 million and build electric cars at its factory in Flat Rock, Michigan.
While campaigning for the presidency, Mr Trump repeatedly said he would not allow Ford to open a new plant in Mexico.
Ford CEO Mark Fields says a range of factors influenced the decision to cancel the Mexican plant, including slower demand for small cars and what he calls Donald Trump's pro-growth policies.
These include cutting the corporate tax rate to 15 per cent and reducing fuel efficiency benchmarks.
"Overall regulatory burdens that are on businesses and he has said very clearly he wants to create a very positive business environment for business to invest in the US and we'll have to see how that rolls out but again this is a vote of confidence and we feel very good about that kind of direction."
When pressed on what Donald Trump might have offered Ford, Mark Fields denied there was any deal.
"Well first off we didn't cut a deal with the President-elect. We did what's right for our business, first and foremost, that's what drives us in every business decision that we make. But we look at a lot of factors and one of the factors that we see is again this more positive US environment for manufacturing and investment here and we take that into account in our investment decisions."
Dr James Nolt is a Senior Fellow at the World Policy Institute at New York University.
He suspects other US companies that have sent jobs offshore will now be working out how much it will cost to re-establish operations in the United States.
"I've already read that Apple, for example, has done a contingency study to see how much it would cost if they moved manufacturing back from China to the United States. Other companies are probably doing the same sort of thing - making contingency plans. What if Trump is really serious about this? How could it affect our costs? How could we reallocate production to be able to take advantage of this new environment? So, a lot of companies and people are assessing Trump to see whether he's serious, or whether his campaign rhetoric was hollow, and I think, increasingly, the evidence is he's serious."
In other developments, within hours of tweeting his disapproval for Republican party plans to weaken the powers of Office of Congressional Ethics, the decision was suddenly dropped at an emergency meeting.
Mr Trump also attacked the cost of Obamacare (Affordable Care Act) and argued against any further releases from Guantanamo Bay in Cuba.
And in delivering his first speech as Senate minority leader, New York Democrat Chuck Schumer implored Donald Trump to tweet less.
"Our challenges (are) too entrenched for mere tweeting. Making America great again requires more than 140 characters per issue. With all due respect, American cannot afford a Twitter presidency. We have real challenges, we have real needs to get things done and many Americans are afraid, Mr President-elect, that instead of rolling up your sleeves and forging serious policies, for you, Twitter suffices."
