The Croatian State Institute for Nuclear Security is playing host to this exercise, organised under an agreement with the Vienna-based Comprehensive Nuclear Test Ban Treaty Organisation (CTBTO).
The Comprehensive Nuclear Test Ban Treaty has been signed by 176 countries, including Croatia. Croatia ratified the document in 2002, along with 133 other countries.
Addressing a press conference today, a Croatian representative said that this exercise was not military but civilian.
The exercise brought together 64 experts from 20 countries. It ends on 24 July.