President Donald Trump’s promised crackdown on illegal immigration has begun to take shape in San Diego County, as federal agents launched targeted operations to arrest undocumented immigrants and a wave of military troops got to work reinforcing U.

San Diego Unified is reinforcing its stance to protect students from federal immigration enforcement at schools. Why it matters: President Trump's executive orders have set the stage for mass deportations and reversed long-standing policies restricting ICE raids in schools.

Among the obstacles for Trump’s mass deportation campaign are the countries refusing to take back their undocumented migrants.