Oil rose the most in six weeks as President Donald Trump affirmed plans to impose tariffs on the top two suppliers of crude to the US.

West Texas Intermediate futures climbed about 2.5% to settle above $70 a barrel after Trump said in a social media post that the proposed levies on Canada and Mexico will go into effect on March 4. 

The tariffs threaten to disrupt North America’s tightly integrated oil industry and raise demand for US crude to backfill any Canadian or Mexican barrels that are diverted elsewhere to avoid the levies. Still, the tariffs’ effects may be blunted by the fact that many American refineries were built to handle those countries’ heavy crudes, rather than domestically produced light oil, leaving them limited options for substitution. The US receives about about 4 million barrels a day from Canada and about 400,000 barrels a day from Mexico. 

Even with Thursday’s gain, crude is still on track for its biggest monthly loss since September as the prospect of trade wars weighs on the outlooks for economic growth and energy demand in the US and China, the world’s two largest consumers. Prices had settled on Wednesday at the lowest since Dec. 10, following conflicting announcements from the White House on the various trade levies under consideration. In his post on Thursday, Trump also said China will be charged an additional 10% tariff from March 4.

“The jury is very much out on how the political and economic agenda of Donald Trump will impact growth,” said Tamas Varga, an analyst at PVM Oil Associates Ltd. in London. “Reciprocal tariffs, tax and spending cuts could elevate inflationary pressure and dent economic prosperity.”

There are also tentative signs that barrels in some regions could begin to flow again. OPEC member Iraq said that it had reached a pact with Kurdistan to resume crude exports through a pipeline shuttered for almost two years, without providing a time frame. An imminent restart of the link has been touted many times before without coming to fruition.

Ukraine President Volodymyr Zelenskiy will visit the US on Friday, Trump said. That comes as the US continues discussions to end the three-year war, a potential shift that could spur a loosening of sanctions on Russian flows.

Possible supply constraints are possible as well, including renewed US efforts to squeeze flows from Iran and Venezuela, along with expectations that OPEC will once again defer a plan to progressively raise output. 

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