Updated 10:54 a.m. | President Donald Trump on Friday demanded Canada “open their markets and take down their trade barriers!” as he threatened more tariffs against America’s northern neighbor.

Trump alleged in a tweet that Canada has “treated our Agricultural business and Farmers very poorly for a very long period of time,” calling the Canadian government “Highly restrictive on Trade!”

He singled out the timber and lumber industries.

Canada has treated our Agricultural business and Farmers very poorly for a very long period of time. Highly restrictive on Trade! They must open their markets and take down their trade barriers! They report a really high surplus on trade with us. Do Timber & Lumber in U.S.? — Donald J. Trump (@realDonaldTrump) June 1, 2018

The tweet came after Trump issued a warning to Canadian officials on Thursday evening, saying he could be on the brink of ending talks about revamping the North American Free Trade Agreement.