The long journey toward ratification of a trade deal between the European Union and the United States has encountered another possible obstruction after authorities in Washington announced an investigation into what they called "excess capacity and production in manufacturing sectors" of a number of trade partners, including the EU.

The US trade representative's office on Wednesday unveiled the investigation, which will likely help the Trump administration raise duties back to the level they were before the US top court last month ruled the president could not use emergency powers to impose tariffs, according to a Financial Times report.

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Other countries affected by the proposed new investigations include China, Mexico and India, but Europe is of particular note because the finalization of the deal is close, and also with the added context of strained relations between the two sides over the US territorial designs on Greenland.

In June last year, following Washington's imposition of tariffs on the bloc, the two parties came to an agreement known as the Turnberry Deal, covering trade between Europe and the US, which, after much internal wrangling on the European side, looked to be on course to be voted on by the European Parliament before the end of this month.

But in the light of a US Supreme Court ruling earlier this year that struck down many of President Donald Trump's tariff policies, Washington is now trying an alternative approach to apply levies on goods foreign countries or trade blocs want to sell to the US.

"The president's trade policy remains the same that it's been for him for decades, which is we need to protect American jobs and we need to make sure we have fair trade with our trading partners," said US Trade Representative Jamieson Greer, adding: "The tools may change."

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Following the Supreme Court rejecting many of Trump's tariffs, EU lawmakers have been eager to get guarantees that they will not face tariffs higher than the 15 percent figure set out in the Turnberry deal, hence the slow progress in ratifying it.

Greer criticized this approach, saying the US had "quickly" complied with what was expected of it, but that application of the expected changes on the European side had been "pending for many, many, many, many months".

"The Europeans agreed in the Turnberry deal that we could have a certain amount of tariff on them, so we're striving for continuity," he said. "We've modified our tariffs accordingly. We're still waiting for Europe to do a lot of what it promised."

Contact the writers at julian@mail.chinadailyuk.com