More than 6,000 migrants have swum or waded from Morocco to the Spanish enclave of Ceuta in recent days, ratcheting up tensions and prompting Spain to deploy troops to the North African outpost.

“We are going to restore order to the city and its borders,” Spanish Prime Minister Pedro Sánchez said in a televised address Tuesday, categorizing the mass arrival of migrants as a crisis.

Ceuta, a port city that borders Morocco and is separated from the rest of Spain by the Mediterranean Sea, “is as much Spain as Madrid, Seville or Barcelona,” Spanish Interior Minister Fernando Grande-Marlaska told reporters Tuesday. He added that at least 2,700 of the migrants have been returned to Morocco and that Spain will be “forceful” in defending its borders.

Ceuta has long been a magnet for migrants from across Africa who hope to claim asylum in Europe, but the record number of arrivals comes at a moment when relations between Spain and Morocco are already strained.

Brahim Ghali, whose Polisario Front movement seeks to make Western Sahara independent of Morocco, has been receiving medical treatment in Spain since last month. Morocco has sharply criticized Spain’s decision to let Ghali into the country, and warned that there could be ramifications. As a result, some analysts think that Moroccan officials are deliberately doing little to stop the flow of migrants into Ceuta.

“This is happening because of the absolute passivity of the Moroccan authorities,” Ceuta regional leader Juan Jesús Vivas Lara told local broadcaster 24H, according to Reuters.

A chaotic scene began to unfold Monday morning as migrants started arriving on Ceuta’s beaches in large numbers, with many swimming around breakwaters or paddling makeshift dinghies to the shore. Others waited until low tide to wade into the territory, or scrambled over security fences, video footage shows. The unprecedented influx of migrants included at least 1,500 minors, Spanish officials said.

“I saw on Facebook that it was possible to cross the border, so I took a taxi here with my friend as I can’t feed my family anymore,” one 26-year-old Moroccan woman told AFP.

Red Cross officials in Ceuta said that they were “absolutely overwhelmed” by the number of arrivals, many of whom required treatment for hypothermia after plunging into the chilly water. At least one migrant died during the crossing, Spanish authorities said.

Spain responded by sending hundreds of additional soldiers to guard the beach on Tuesday as migrants continued to arrive in Ceuta, although in lower numbers.

A long-standing agreement that Moroccans cannot be granted asylum in Spain meant that many migrants were quickly deported after arriving in Ceuta. However, unaccompanied minors are eligible to remain in Spain under government supervision, and Spanish authorities said that none had been returned to Morocco.

Moroccan authorities did not immediately respond to a request for comment and have not made any public statements about the massive surge of migrants. Meanwhile, the European Union has called on Rabat to do more to prevent migrants from setting out for Ceuta.

“The most important thing now is that Morocco continues to commit to prevent irregular departures and that those that do not have the right to stay are orderly and effectively returned,” Ylva Johansson, the European Union’s commissioner for home affairs, said Tuesday. “Spanish borders are European borders.”

The relationship between Madrid and Rabat has long been complicated by the issue of Western Sahara, a disputed territory that was occupied by Spain until 1975 and is now claimed by Morocco. Spain does not recognize those claims, but has said that providing medical treatment to the leader of the Polisario Front militants was a humanitarian decision rather than a political one.

In an apparent effort to play down tensions, Spanish Foreign Minister Arancha González Laya said Tuesday that she did not believe that “putting the lives of young people and minors at risk” was a retaliatory move. Sánchez and other top government officials have similarly steered clear of any direct criticism of Morocco.

The status of Ceuta and Melilla, another Spanish enclave in North Africa, have also been a source of controversy. At times, Rabat has suggested that both cities should really be part of Morocco, a notion that Madrid vehemently opposes.

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