While U.S. President Donald Trump threatens tariffs over wildfire smoke drifting south, Canadian fire experts say large forest fires are inevitable. 

Over the past week, Trump has criticized Canadian fire management and said the country is “poisoning” U.S. air. He suggested Canada might have to pay. 

But experts say Canada’s worsening fire seasons reflect a harder reality: not every blaze, or the smoke that comes from it, can be stopped. 

“Saying that you would need to extinguish very huge fires like this is similar to trying to stop a hurricane,” said Martin Girardin, a forest ecology researcher with Natural Resources Canada’s Canadian Forest Service. “It’s just unstoppable.”