The document proposes using an ensemble of K-nearest neighbor classifiers optimized with genetic programming for intrusion detection. It trains multiple K-NN classifiers on subsets of the KDD Cup 1999 intrusion detection dataset and then uses genetic programming to combine the classifiers to improve performance. Results show the ensemble approach reduces error rates compared to individual classifiers and the genetic programming-based ensemble achieves an area under the ROC curve of 0.99976, outperforming the component classifiers.