The proliferation of Unmanned Aerial Vehicles (UAVs) is both a benefit and threat to the security of the United States. The use of UAVs by terrorist poses a serious threat to the American public if left unaddressed. By comparing the capabilities provided by UAV and our current security measures, it is easy to see the gaping holes in our current protection. These gaping holes in our security coupled with the terrorist predisposition to use aerial assets as a primary method to conduct terrorist attacks highlight the urgency of the threat.Identifying and understanding the threat is just the first part of the problem. The challenge is combating this emerging threat. The rapid proliferation in the public and private sector makes identifying, tracking and disabling UAVs used for terrorist activities extremely difficult. The solution will require a comprehensive approach comprising public education, UAV marking, tracking of key components and changes in current security measures.Only by acknowledging the threat and implementing significant changes can we hope to avoid another aerial attack on American soil. The recent terrorist attacks in Paris and around the world highlight the difficulty governments' encounter preventing terrorist from injuring and killing innocent people in public places. These attacks are not a result of weak government or poor security but more the results of determined extremist exploiting vulnerabilities in security measures to inflict harm and cause fear. Protecting the public is a massive responsibility of every government and requires maintaining existing security measures as well as adjusting to new emerging threats. Often these new threats are the result of changes in technology or tactics used by various terrorist organizations. The challenge for the agencies charged with protecting the public is accurately identifying these changes and adapting appropriate countermeasures. This continues to be a struggle for governments around the world. Unfortunately, the future appears more difficult as technology continues to expose new areas for terrorist exploitation.Today, the challenge for governmental agencies and local law enforcement is the development of the Unmanned Aerial Vehicle (UAV). In the hands of criminals and terrorist, this transformational technology could be devastating. To put it bluntly, the proliferation of UAVs coupled with terrorist characteristics to exploit technology and invoke fear makes the use of UAVs a clear and present threat to the United States. This paper will show the developing UAV technology provides increased opportunities for terrorist to exploit current security vulnerabilities while remaining consistent with established patterns of terrorist behavior. The characteristics of UAVs, not only increase the access to high profile targets, in many cases, it would potentially reduce the risk of apprehension and the associated cost.We will start with a basic understanding of terrorism and the motives behind most terrorist attacks directed at the United States. Then from that perspective show how the UAV capabilities could easily be used to conduct terrorist attacks in the United States and abroad. For this, we will focus on the specific element of aerial terrorism, which has been a long held tactic of terrorist. By connecting the intended terrorist goals, the UAV capabilities and the historic tendencies of terrorist organizations, we can project the possible use of UAVs in future attacks. Only then will we be able to look for counter measures to offset the advantages presented by the developing UAV technology.This compilation includes a reproduction of the 2019 Worldwide Threat Assessment of the U.S. Intelligence Community.