in this section   Read the full report   (PDF)

This working paper discusses the decoys used for the eighth Ground Based Mid-Course flight test, IFT-8, and how the defense used the kill vehicle’s infrared sensors to discriminate these decoys from the mock warhead.  While increasing the number of decoys increased the complexity of this test, the additional balloons did not increase the difficulty of the discrimination task.  They therefore did not represent a significant increase in the realism of the test.

Moreover, as in the previous tests, discrimination relied on the defense having detailed prior knowledge about how all the objects will appear to the defense sensors—an assumption that is highly unrealistic.