The unstable security nature of the Gulf countries alongside with the previous animosity between Saudi Arabia, United Arab Emirates, and Qatar have led to high military spendings. However, the situation has developed into a security dilemma in the Gulf in which the three countries regard each other as a security concern. As a result, the countries involved have entered an arms race. The thesis investigates the reasons behind the growing arms race between KSA, Qatar, and UAE. To address this topic, I depend highly on observation through deep reading on journal articles, news report, and statements which highlight the topic from different perspectives. Using case study method that provides a compressive study about the three countries, and then explore the phenomenon of arms race within each state. The thesis concludes that Qatar, Saudi, and UAE have faced external security threats to their sovereignty and security posed by GCC countries and as well by non-GCC countries, Iran, and Yemen, which drop them into an arms race. Finally, the thesis believes that although there is no apparent conflict between Saudi Arabia, UAE, and Qatar, the arms race in the GCC region have grown due to the lack of trust between the three countries and the divergent in threat's perception.