“This is an act of defiance,” Spain’s prime minister, Pedro Sánchez, told parliament on Wednesday. “The lack of border control by Morocco is not only a show of disrespect of Spain, but rather for the European Union.” After thousands of people, including an estimated 2,000 minors, crossed into Spain in 36 hours earlier this week, arrivals into Ceuta had all but halted on Wednesday as Morocco tightened control of the border. The diplomatic tensions between Madrid and Rabat, however, continued unabated. Spain’s prime minister flew to the country’s North African enclave Tuesday to contain a migration crisis with neighboring Morocco after 6,000 migrants swam or walked over the border. Spain deployed troops and extra police to repel crowds who were trying to get around security fences from Morocco into the tiny Spanish territory after a huge incursion of migrants the day before. Videos emerged that appeared to show Moroccan soldiers opening security gates to let migrants through to the Spanish port city. European Union leaders backed Spain, saying the mass incursion in Ceuta was a breach of the bloc’s borders. Experts suggested this huge influx, which included entire families, was an attempt by Morocco to pressure Spain to alter its policy toward Western Sahara, the disputed territory to which Rabat lays claim.