The Washington Post reports about 100 people have joined the Islamic State militant group from countries in the Caribbean and South America, and existing human smuggling networks are in place that could allow them to infiltrate the United States if they return, said a top U.S. general on Thursday. Marine Gen. John F. Kelly, chief of U.S. Southern Command, told the Senate Armed Services Committee that the networks are “so efficient that if a terrorist or almost anyone wants to get into our country, they just pay the fare.” “No one checks their passports,” the general said. “No one, you know, they don’t go through metal detectors. No one cares why they’re coming. They just ride this network.“ More than 15,000 foreign fighters have poured into the Middle East to join the Islamic State, traveling primarily to Syria. Kelly, who oversees U.S. military operations in Central and South America and the Caribbean, acknowledged that the number of fighters coming from his region is small, but said that the countries involved don’t have the ability to monitor those returning well.