homeland security
noun uk/ˌhəʊm.lænd sɪˈkjʊə.rɪ.ti/ us/ˌhoʊm.lænd sɪˈkjʊr.ə.t̬i/
[ U ]（美国）国土安全（活动或机构）
activities and organizations whose purpose is to protect the US from attacks within the country by terrorists
Homeland Security （美国）国土安全部
the department of the US government that deals with homeland security