Mexican security forces have detained about 475,000 irregular migrants since October, authorities said on Friday, as U.S. President-elect Donald Trump threatens Mexico with tariffs unless it stops illegal migrants from arriving at the shared border. Nearly half a million migrants being detained between Oct. 1 and Dec. 26 suggests measures intensified towards the end of the year. Since the start of the year, some 900,000 migrants have been detained, the government said earlier this month.