President Donald Trump said on Monday that Mexico should send Central American migrants seeking asylum in the United States back to their home countries, a day after U.S. authorities shut the country's busiest border crossing and fired tear gas into a crowd there.

Sunday's incident, which took place in response to a group of migrants from the Mexican side rushing at the border fencing, was the latest chapter in a saga that has pitted Trump's hard-line stance on immigration against thousands of migrants who have made their way north through Mexico from violent and impoverished Central American countries.

Tensions had been growing in Tijuana and Trump announced on Saturday that the migrants would have to wait in Mexico until their individual asylum claims were resolved in the United States, a significant shift in U.S. asylum policy that could keep Central Americans in Mexico for more than a year.