President Claudia Sheinbaum is detaining more migrants, seizing more fentanyl and positioning her country as a key ally against China. But the U.S. stance has shifted, too.

WASHINGTON - Newly sworn-in U.S. President Donald Trump said on Monday that he would declare illegal immigration a national emergency, send troops to the U.S.-Mexico border, and reinstate his "remain in Mexico" policy as part of a sweeping immigration crackdown.

President-elect Donald Trump will declare a national emergency at the U.S. southern border with Mexico on Monday and announce plans to send additional armed forces to help secure the border, an incoming Trump administration official said.

President Trump invoked muscular presidential powers to begin a sweeping crackdown on immigration following his inauguration on Monday, tasking the military with border enforcement, moving to designate cartels and gangs as terrorist groups,