The present study examines the (de) legitimization strategies used in the statements made by diplomats from Saudi Arabia, the United Arab Emirates, Bahrain and Egypt, the four Arab states that severed ties with Qatar on June 5, 2017 for supporting and funding terrorism, in interviews, press conferences, and UN Security Council meetings. It also examines these strategies in the statements made by the U.S. State Department spokesperson in Department press briefings. Employing van Leeuwen's (2007) and Reyes' (2011) (de) legitimization strategies, the study also investigates the linguistic devices used to realize the (de)legitimization strategies as well as the functions that these strategies and their linguistic realizations fulfill. The study shows that diplomats from the Arab quartet use a number of (de)legitimization strategies, such as authorization, moral evaluation, a hypothetical future, and altruism, to directly and explicitly legitimize the decision to boycott Qatar and delegitimize its policies. It also reveals that the U.S. indirectly and implicitly delegitimizes boycotting Qatar, and explicitly legitimizes Qatar's efforts to fight terrorism and extremism as well as Kuwait's mediation efforts. The study develops the strategy of posing unanswered questions which is used to legitimize some actions and delegitimize others.