The U.S. Homeland Security Chief Jeh Johnson says the United States is increasing security at certain overseas airports with direct flights to the United States. Johnson said Wednesday his department continually accesses the global threat environment and reevaluates measures to promote airport security. He gave no information on what prompted the latest move or which airports are involved. _________________ 美国国土安全部部长杰`约翰逊表示美国正在加强某些直飞美国本土海外机场的安保工作.周三约翰逊称,国土安全部持续监控全球安全威胁,并重新评估提高机场安全的各种措施.而对推动这些举措的原因及涉及的机场,他没有透露任何信息._________________