At present,military equipment,systems and civil infrastructure are facing increasingly serious electromagnetic pulse (EMP) threat.The United States has been strengthening the assessment and defense of EMP threat.To fully un-derstand and analyze the current situation,problems and policies of EMP defense in the United States,the series of assessment reports issued by EMP Commission,the president executive order and important documents issued by the United States government such as “National Defense Authorization Act” are researched.The EMP threat environ-ment,scenes and responsive strategies in the United States,and the roles,responsibilities and tasks of relevant de-partments and heads of the federal government are analyzed.It is noted that the U.S. currently aims to ensure U.S. security by establishing strong national executive leadership,organizing and coordinating government and private sector relationships,and promoting technology information sharing to strengthen U.S. critical infrastructure and improve U.S. resilience to EMP threats.