Shoppers head back to the US-Mexico border with their purchases in San Ysidro, California, on November 26, 2024. US President-elect Donald Trump threatened to begin his presidency with a massive trade war -- and diplomatic crisis -- as he demanded China, Canada and Mexico stop illegal immigration and drug smuggling into the United States or face punitive US import tariffs. (Photo by Sandy Huffaker / AFP) (Photo by SANDY HUFFAKER/AFP via Getty Images)