WASHINGTON—The good vibes are gone.

In the clearest public indication that talks over the North American Free Trade Agreement are going poorly, Foreign Affairs Minister Chrystia Freeland blasted the U.S. for the first time on Tuesday while U.S. Trade Representative Robert Lighthizer blasted Canada and Mexico.

They were standing beside each other at an awkward joint appearance in Washington to mark the end of the fourth round of negotiations over the U.S.-initiated effort to revamp the 23-year-old continental free trade pact.

Prime Minister Justin Trudeau and members of his government, including Freeland, had until Tuesday maintained a chipper public tone about the talks even as the mood at the bargaining table darkened.

No longer. Freeland denounced the U.S. for “an approach that seeks to undermine NAFTA rather than modernize it,” warning that the “unconventional” proposals from President Donald Trump’s administration would “turn back the clock” and put tens of thousands of jobs at risk.

Lighthizer, meanwhile, criticized both Canada and Mexico for what he called a “resistance to change,” saying he was “surprised and disappointed” they were obviously acting to defend the “unfair advantage” possessed by Canadian and Mexican companies.

The three parties announced that they would take the trade equivalent of a timeout, starting the fifth round of negotiations a month from now rather than their usual two weeks.

In a joint statement, the three countries agreed there were “significant conceptual gaps among the parties.” They said they had “called upon all negotiators to explore creative ways to bridge these gaps.”

They spoke at the end of a weeklong round at which U.S. negotiators delivered demands so unpalatable to Canada and Mexico that trade experts were left wondering if Trump, who has been publicly noncommittal, preferred to blow up the talks rather than reach a new deal.

Freeland and her office previously criticized specific U.S. proposals. But this was the first time she, or any other top Canadian official, publicly expressed broad concern about the state of the talks or the American approach.

Freeland was most forceful on the subject of U.S. automotive proposals, warning that they would “put in jeopardy tens of thousands of jobs across North America.” Among other significant changes, the U.S. has proposed a new rule requiring that 50 per cent of car content be made in the United States.

“We have said this from the beginning: we will maintain and defend the elements of NAFTA that Canadians consider essential to the national interest,” she said.

Lighthizer railed against trade deficits, which economists say are inconsequential but Trump considers paramount.

“We have seen no indication that our partners are willing to make any changes that will result in a rebalancing and a reduction in these huge trade deficits,” Lighthizer said — minutes after Freeland noted that the U.S. actually has a trade surplus with Canada.

Trudeau had professed “optimism” during a visit to Washington last week. He did, however, acknowledge Trump’s unpredictability, and he said repeatedly that Canada was “ready for anything.”

The current list of U.S. demands vehemently opposed by Canada includes:

• A “sunset clause” that would automatically terminate the deal in five years if all three countries did not endorse it again at that time.

• A rule requiring all cars to be made with 50 per cent American content if they are to be exempted from tariffs.

• The dismantling of Canada’s protectionist supply management system for dairy and poultry.

• A “Buy American” procurement policy sharply limiting Canadian and Mexican access to U.S. government contracts.

• The end of the current independent tribunal system for resolving NAFTA disputes.