The Geospatial Technologies and Human Rights Project of the American Association for the Advancement of Science (AAAS) has undertaken analysis of the crisis between Ukraine and Russia in Crimea using high-resolution satellite imagery. This analysis forms part of a broader study aimed at investigating cross-border conflicts to identify early warning signs to aid in future conflict prevention efforts. The first report in the series focuses on the Sevastopol. Analysis of the port city of Sevastopol, which houses the Russian Black Sea Fleet, has revealed a number of observations that can be considered warning signs of a potential armed conflict. These include the movement of combat and logistics vehicles, the construction of roadblocks, and the establishment of a maritime blockade of strategic ports and harbors. Particularly in the case of maritime actions, these observations suggest a level of coordination and organization consistent with the interpretation that the armed groups which seized control of Crimea in February-March 2014 were not solely “spontaneous self-defense militias”. The apparent use of Russian naval vessels to blockade the port of Sevastopol strongly suggests that such actions are at the very least supported by the Russian military. Of course, alternate interpretations of the imagery are possible, particularly with respect to the deployment and disposition of land-based forces. Nevertheless, when viewed in light of reports alleging the presence of Russian troops on the ground alongside irregular units, this analysis lends credibility to the involvement of Russian military forces in the takeover of Sevastopol. Upcoming reports in this series will focus on other Russian and Ukrainian military bases throughout Crimea to determine whether high-resolution satellite imagery can provide further clarification of this evolving situation, and identify further warning signs of a possible future armed conflict between these two countries.