The first ever production of controlled thermonuclear energy, using a mixture of deuterium and tritium plasma, was achieved with the JET Tokamak experiment on the 9th of November 1991. A fusion power of 1.7MW was obtained in a pulse 2s long. The construction of JET, the flagship of the Fusion Research Programme of the European Community, took place between 1978 and 1983. Then the experimental programme started. JET plasmas have already approached equivalent conditions to those needed in a thermonuclear reactor, although only transiently, due to the high influx of impurities from the vessel walls. This problem, the main threat to the development of a fusion reactor, will be addressed in the next phase of JET development (1992-96) using a new pumped divertor magnetic configuration. The expected experimental results will provide a further major contribution to the engineering design of the 'next step' device, ITER, a cooperative effort, presently under way, between Europe, United States, Russia and Japan. ITER will be a prototype thermonuclear reactor aimed at producing fusion power in excess of 1,000MW.