The NATO N4 corpus contains speech collected at naval training schools within several NATO countries. The speech utterances comprising the corpus are short, tactical transmissions typical of NATO naval communications. In this paper, we report the results of some preliminary speaker recognition experiments on the N4 corpus. We compare the performance of three speaker recognition systems developed at TNO Human Factors, the US Air Force Research Laboratory, Information Directorate and MIT Lincoln Laboratory on the segment of N4 data collected in the Netherlands. Performance is reported as a function of both training and test data duration. We also investigate the impact of cross-language training and testing