Americans want payback for smoky skies. Are they right?

People on both sides of the Canada - U.S. border have been choking on smoke in recent weeks, much of it coming from fires burning in Canada's forests. Now, U.S. President Donald Trump is threatening new, fire-related tariffs in retaliation. Climate scientists like Zeke Hausfather say wildfires in Canada’s vast boreal forest are linked to global warming and can't be blamed on just one country. And environmental law expert Godwin Dzah explains, when health hazards cross borders there are ways to hold governments and companies to account. But the question of liability gets hazy when climate change enters the conversation.