About 8,000 people have streamed into the Spanish city of Ceuta from Morocco in the past two days in an unprecedented influx, most of them swimming around breakwaters and across the border to reach the Spanish enclave in North Africa. The surge has strained relations between Morocco and Spain. Spanish Prime Minister Pedro Sánchez canceled a trip to Paris to make an unscheduled visit to Ceuta, where Spain has deployed military reinforcements and police along the border. The developments in Ceuta have become one of the biggest crisis in relations between Spain and Morocco since 2002. Many suspect it is partly retaliation against Spain for having allowed the leader of a militant group fighting Morocco to receive medical treatment in Spain.