This study explores the role of social media in foreign policy,and the impact social media use has on foreign policy decisions.It takes the form of a case study,examining Donald Trumps use of Twitter in diplomacy.　　Having established that Donald Trump makes little use of social media in foreign policy,the analysis identifies the relevant cases where he uses social media and the impact those instances have had on U.S.foreign policy.　　The study identifies the challenges that come with Trumps use of Twitter for diplomacy on U.S.foreign policy,namely,loss of moral high ground,eroding of normative power and alienation of allies.It concludes that social media use has some benefits in diplomacy,but with the way Donald Trump has utilized it,the negatives outweigh the positives.