Cloud Peak Energy CEO Colin Marshall urged investors Thursday on an earnings call not to get ahead of themselves in worrying about whether coal exports to Canada would be banned. This comes after Premier Christy Clark of British Columbia penned a letter to Canadian Prime Minister Justin Trudeau Wednesday asking him to ban coal shipments from the U.S., sending shares from the coal giant tumbling.

Retaliation against Trump: Trump's new tariffs on Canadian softwood lumber sparked the response from Clark. Trudeau's spokesman said he would consider the request "carefully and seriously," per Bloomberg.

Why it matters: This ban would hit Trump where it would hurt — his campaign promise to bring back coal — since about 6.2 million metric tons of U.S. thermal coal were shipped through Vancouver's sea port in 2016.

Calming the coal fright: Marshall said all planned exports would still be shipped out.