The long and turbulent road to building the world’s largest fusion experiment — from Reagan-Gorbachev diplomacy in 1985 to cost overruns, schedule delays, and the ongoing assembly of a 23,000-tonne machine in southern France.
ITER began as a Reagan-Gorbachev diplomatic initiative at the 1985 Geneva Summit, where the U.S. and Soviet Union agreed to collaborate on fusion. The European Community and Japan joined. After a decade of design work and a U.S. withdrawal (1998–2003), the seven-member ITER Agreement was signed in 2006 by the EU, Japan, Russia, the U.S., China, South Korea, and India.[1]
Construction began in 2010 with an original budget of €5 billion and first plasma planned for 2018. Multiple schedule revisions followed: first plasma was pushed to 2025, then 2035, with costs rising to an estimated €20–22 billion. Challenges include: the complexity of managing in-kind contributions from seven parties; nuclear-grade quality standards; COVID-19 delays; and discovery of manufacturing defects in some components.[2]
As of 2026, the tokamak building (the largest nuclear facility under construction) is complete, and major components including vacuum vessel sectors, toroidal field coils, and the cryostat are being assembled. The ITER Organization underwent management restructuring in 2023–2024 under new Director-General Pietro Barabaschi, who implemented a “New Baseline” schedule.[3]