Proactive information sharing is a challenging issue faced by intelligence agencies in effectively making critical decisions under time pressure in areas related to homeland security. Motivated by psychological studies on human teams , a team-oriented agent architecture -- CAST (Collaborative Agents for Simulating Teamwork), was implemented to allow agents in a team to anticipate the information needs of teammates and help them with their information needs proactively, effectively, and timely. In this paper, we extend CAST with a decision-making module. Through two sets of experiments in a simulated battlefield, we evaluate the effectiveness of the decision theoretic proactive communication strategy in improving team performance, and the effectiveness of information fusion as an approach to alleviating the information overload problem faced by distributed decision makers. Keywords : Homeland Security, Information Overload, Agent Teamwork, Team Decision-making