The Globe and Mail reports in its Tuesday edition that American media stocks tumbled on Monday after President Donald Trump unveiled a 100-per-cent tariff on all movies produced outside the United States, in his latest levies that could sharply raise costs for Hollywood studios. A Reuters dispatch to The Globe says that Mr. Trump's announcement was light on details. It did not say whether the duties will target films on streaming platforms and those shown in theatres, nor did it specify if the tariffs will be calculated based on production costs or box-office revenue. Netflix could particularly be at risk, as it relies on its global production network. Shares of Netflix, Disney and theatre operators all fell. Despite Los Angeles's historic reputation as the hub of cinema, studios have over the years shifted production overseas to locations such as Britain, Canada and Australia to take advantage of generous tax credits and lower labour costs. A forced move back to the U.S. would likely drive up production budgets and disrupt a global supply chain that now includes shooting in Europe, postproduction in Canada and visual effects work in Southeast Asia. Mr. Trump claims the tariffs will address national-security concerns.