WASHINGTON -- Donald Trump's chief economic adviser is citing America's new free trade pact with Canada and Mexico as one of the reasons why the U.S. president is so disappointed with the latest job and production cuts at General Motors.

And Trump himself is crystallizing that disappointment, threatening to pull federal help for the automaker if it follows through on plans to build new interconnected, electric-powered vehicles outside the U.S. -- particularly in China, the president's main trade rival.

Larry Kudlow, director of the National Economic Council, says the disappointment has been amplified by the fact the cuts are coming in the wake of the newly reached U.S.-Mexico-Canada Agreement, one of Trump's signature achievements on trade.

"He believes -- as, frankly the prime minister of Canada, Trudeau, believes -- that the USMCA deal was a great help to the automobile industry and to autoworkers," Kudlow told a White House briefing.

"There's disappointment that it seems that GM would rather build its electric cars in China than the United States, and we are going to be looking at certain subsidies regarding electric cars and others, whether they should apply or not."

GM announced Monday that it plans to close five plants in North America (one in Oshawa, Ont., and four in the United States), cut roughly 14,000 jobs and stop producing several vehicle models.

Even as Tuesday's briefing was taking place, Trump tweeted an ominous threat to withdraw all General Motors subsidies in retaliation for the cuts.

"The U.S. saved General Motors, and this is the THANKS we get!" the president wrote.

"We are now looking at cutting all GM subsidies, including for electric cars. General Motors made a big China bet years ago when they built plants there (and in Mexico) -- don't think that bet is going to pay off. I am here to protect America's Workers!"

Kudlow also made it plain that the agreement would be signed by representatives of all three countries later this week when G20 leaders gather in Buenos Aires for their annual meetings, something that's been in question as Canada and Mexico seek an end to their tariff standoff with the U.S. over steel and aluminum.

Canada has demurred on the question of whether the tariffs would scuttle the signing, but Mexico has been unequivocal, saying it would not put pen to paper so long as U.S. levies on Mexican exports of the metals were still in place.