The paper presents 3 key technologies used in an integrated maritime reasoning and monitoring system . These technologies fuse maritime data for decision support in the martime security domain. They support monitoring of scenarios of interest such as terrorist attacks or piracy incidents, and alert operators when such scenarios are assessed likely to happen. These 3 technologies are: a. Dynamic Bayesian Reasoning & Advanced Intelligent Networks (D'Brain), a reasoning system based on Bayesian networks. Causal and probabilistic information about scenarios of interest are structured as Bayesian networks, in which variables are set according to the interpretation of incoming situation information. The system thus provides a systematic approach to modelling and monitoring for scenarios of interest in the maritime situation. b. Graylist Ranking, a ranking technique to order entities based on their structural relationship with black-listed entities. The ranked list of entities could then be used to prioritize further investigation efforts into higher ranking entities which are considered more suspicious. c. Trajectory Analysis using a nonparametric Bayesian model, Dual Hierarchical Dirichlet Processes (Dual-HDP) . It models the activity patterns (norm) of entities in motion. With the norm established, anomaly detection could be performed by evaluating how much each track deviates from the norm.