In real-world target tracking scenarios, interactions among multiple moving targets can severely compromise the performance of the tracking system. Targets involved in interactions are typically closely-spaced and are often partially or entirely occluded by other objects. In these cases, valid target observations are unlikely to be available. To address this issue, we present an integrated multi-target tracking system. The data association method evaluates the overlap rates between newly detected objects (target observations) and already-tracked targets, and makes decisions pertaining to whether a target is interacting with other targets and whether it has a valid observation. Thus, the system is capable of recognizing target interactions and will reject invalid target observations. According to the association results, distinct strategies are adopted to update and manage the tracks of interacting versus well-isolated targets. Testing results on real-world airborne video sequences demonstrate the excellent performance of the proposed system for tracking targets with multiple target interactions. Moreover, the system operates in real time on an ordinary desktop computer.