Election is an important part of the American political process. In 2016，both the US electoral infrastructures and voters’ information environment were disturbed in various degrees，which exposed election flaws and frustrated the public. Since Trump took office，election security has become a vital topic in US homeland security and national security. To prevent potential threats in future elections，the US Federal and local governments have proceeded in multiple layers to enhance the system’s ability of resistance，including improving the performance of electoral infrastructures，weakening the “influential campaign”，organizing in “whole-of-government” approach，and reinforcing its ability of deterrence. These actions will mitigate the risks to the current US electoral system in short run but also encounter various political and institutional obstacles. It is of great significance to understand the US homeland and national security strategy in the lens of election security.