[en] Full text: Not just one, but a series of combined events has led, through an abundance of prudence, to a systematic development and deployment of a nuclear detection architecture in the USA. There have been troublesome reports that non-national terrorist entities have been striving to acquire nuclear material - both radioactive sources and weapons usable material - since the early 1990s. There have been two World Trade Center attacks using unconventional weapons, the second attack being fully successful. Threat streams of even greater attacks are continuing. The terrorist adversary has proven adaptive and persistent. Additionally, not all State actors have embraced the abolishment of terror tactics; thus, we cannot ignore those States as possible surreptitious users of nuclear or radioactive material as weapons, should diplomacy fail. We do not believe that nuclear stockpiles are one hundred per cent secure in some nations, and that diversions may have occurred or could still occur. Combine this with radicalism, motive and intent, and we are compelled to strive to create an effective detection architecture that may deter or prevent illicit nuclear or radioactive material trafficking. Our primary intent is to secure our borders and support our partners, and some of this work involves strengthening partnerships with other countries and entities, the IAEA being one of those entities. Arguably, there have been about 20 cases of illicit nuclear trafficking where actual weapons usable material was seized (many more in which other radioactive material was involved). This is 20 cases too many, and we cannot know whether this is only the tip of the iceberg. The paper describes the US Government origins of the development of an effective illicit nuclear trafficking detection architecture, the centralized planning involved and the shared responsibilities of numerous US Government agencies. Our belief is that end to end planning, a robust nuclear forensics capability, a global initiative and other related activities are part of this architecture. Lastly, the paper offers an information sharing strategy, which will be imperative in order for our many systems to work together effectively. (author)