# Software aspects of strategic defense systems > A collection of eight essays on why the software system required by SDI, the so-called “Star Wars project,” cannot be built. A collection of eight essays on why the software system required by , the so-called "Star Wars project," cannot be built. > On 28 June 1985, , a respected computer scientist who has consulted extensively on United States defense projects, resigned from the Panel on Computing in Support of Battle Management, convened by the Strategic Defense Initiative Organization (SDIO). With his letter of resignation, he submitted eight short essays explaining why he believed the software required by the Strategic Defense Initiative would not be trustworthy. Excerpts from Dr. Parnas's letter and the accompanying papers have appeared widely in the press. The Editors of American Scientist believed that it would be useful to the scientific community to publish these essays in their entirety to stimulate scientific discussion of the feasibility of the project. As part of the activity of the Forum on Risks to the Public in the use of computer systems the Editors of Communications are pleased to reprint these essays. https://web.stanford.edu/class/cs99r/readings/parnas1.pdf#page=1.36 Contents: 1. The fundamental technological differences between and other areas of engineering and why software is unreliable 2. The properties of the proposed SDI software that make it unattainable 3. Why the techniques commonly used to build military software are inadequate for this job 4. The nature of research in software engineering, and why the improvements that it can effect will not be sufficient to allow construction of a truly reliable strategic defense system 5. Why I do not expect research in [artificial intelligence](https://wiki.g15e.com/en/pages/Artificial%20intelligence.txt) to help in building reliable military software; 6. Why I do not expect research in to bring about the substantial improvements that are needed 7. Why military funding of research in software and other aspects of [computing science](https://wiki.g15e.com/en/pages/Computer%20science.txt) is inefficient and ineffective. ## Notes About 40 years have passed since these essays were written (as of <2025>). Major changes since then: - , for which computing power was considered woefully inadequate at the time, has become practical enough to use. (For example, [Lean](https://wiki.g15e.com/en/pages/Lean%20(programming%20language.txt)).) - Although it was considered difficult to calculate events in the complex analog world quickly enough, computers have become so fast that we can simulate large-scale physical phenomena with meaningful accuracy. - [Neural networks](https://wiki.g15e.com/en/pages/Artificial%20neural%20network.txt), which were too toy-like even to be mentioned then, are now practically swallowing the world. Of course, military use will surely require integrating .