A day after U.S. agents fired tear gas to repel migrants breaking through the border fence in Southern California, Homeland Security officials defended the use of force and their decision to close the country’s busiest port of entry, saying they expect additional confrontations and shutdowns.

Facing dismal conditions in Mexico and long waits for the chance to request asylum in the United States, thousands of Central American migrants are becoming more agitated, and officials see no quick resolution to the tensions that erupted Sunday. …

On Monday, critics of the Trump administration denounced border agents’ use of force on groups that included families with children, but U.S. officials praised what they called “quick and effective action” against crowds of stone-slinging young men who pried open the border fence at multiple locations to squeeze through.