From what I understand it was the downscaling that politicians demanded to reduce costs that caused most of the cost increase. Lots of design parameters had to

From what I understand it was the downscaling that politicians demanded to reduce costs that caused most of the cost increase. Lots of design parameters had to be changed as a result of it, new technologies developed to get things to work on the smaller scale, etc. There was also a lot of mismanagement in the beginning, with the Japanese management being completely new to the area (the director general was Japan's former ambassador to Croatia). Later, management was restructured several times and now people with experience in plasma physics are in charge. Source: A retired nuclear fusion physicist who was indirectly involved in ITER told me this.