NATO anti-terrorism naval patrols have begun operating up and down Spain's southern coast. Earlier, the European Union began anti-immigration patrols in the western Mediterranean. Hundreds of thousands of Arabs and Africans cross the Straights of Gibraltar to enter Spain. Some of these illegal migrants were later found to be involved in terrorist activity. But a larger reason is the growing hostility of Spanish and Italian civilians towards the illegal migrants, who tend to increase the crime rate and compete with the locals for scarce jobs. The navy ships and aircraft assigned to the patrols join coast guard ships already in action.