Migrants in Mexico who were hoping to come to the U.S. are adjusting to a new and uncertain reality after President Donald Trump began cracking down on border security.

The US-Mexico border is effectively closed off to migrants seeking asylum in the United States within hours of President Donald Trump taking office, an extraordinary departure from previous protocols that has left many concerned migrants in limbo.

Active duty military troops will begin arriving in El Paso, Texas, and San Diego on Thursday evening, in what defense officials said is the first batch of the new forces being deployed to secure the southern border.

Active-duty military personnel began arriving along the southern border Thursday evening after President Donald Trump declared a national emergency to address the immigration crisis.

Troops have assisted at the border before and will be limited to support roles unless the administration invokes the Insurrection Act.

Washington — 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, shutting down asylum and refugee admissions and attempting to terminate birthright citizenship.

The U.S. southern border has seen a sharp drop in migrant encounters entering between ports of entry at the southern border, according to a CBP source.

U.S. President Donald Trump's administration has directed prosecutors to investigate officials who resist immigration enforcement efforts, intensifying a sweeping crackdown that Trump launched the day he took office.