Thousands of migrants swam to Ceuta, a Spanish autonomous city on Morocco's northern coast. The mass movement triggered a political crisis in Spain.
The Madrid government decided to send troops to the area to respond. The incident signals a renewed flare-up of migration pressure on the European Union's external borders.
In Spain, the right-wing opposition accuses Prime Minister Pedro Sánchez of failing to take adequate measures against the migrant influx. The crisis has sparked fierce debate within the country.
Italian Foreign Minister Antonio Tajani issued a sharp statement, calling for Spain's Schengen membership to be suspended. The demand once again laid bare deep divisions over migration policy within the EU.
The unimpeded crossing of such a large group has also led to allegations that the Moroccan government turned a blind eye to the process.