The European Union (EU) is considering going it alone with plans to build ITER, an international attempt to develop fusion as an energy source.

Research ministers from EU member states will discuss plans to build the €4.7-billion (US$6.1-billion) device without the help of international partners when they meet in Brussels on 25 and 26 November. Officials at the European Commission, the EU's executive arm, stress that this is a fall-back position should arguments over where to site the reactor not be resolved.

Hopes for a resolution are not high. France and Japan have both proposed sites for the reactor, which will attempt to create fusion energy by heating a plasma constrained in a magnetic field. The proposals are considered to have equal merit, and parties have been deadlocked for more than a year. European nations want the reactor to be based at Cadarache in France; the United States and South Korea favour the Japanese site at Rokkasho.

The latest international meeting, held on 8 and 9 November in Vienna, ended yet again without decision. The dispute attracted attention when the Reuters news agency reported that an EU official had said that Japan was going to back the French site. Japanese officials angrily denied the story and, according to a European source, stiffened their resolve not to back down.

EU ministers will now consider an analysis of their ability to host the project without Japan, South Korea and the United States. That trio are currently offering to provide 30–40% of the construction and launch costs, says Fabio Fabbi, commission spokesman for research. He says the commission will consider asking for extra funding from France, Russia and China, or find cheaper ways of building the reactor.

“For both financial and technological reasons, I think that would be very difficult,” says Takahiro Hayashi, deputy director of Japan's office of fusion research. “This has always been a project based on international cooperation. Giving up on that would be deplorable.”

EU ministers may decide to continue negotiations. Details of the Vienna talks have not been revealed, but it is believed that Japan was offered a deal under which it would end its bid to be host in return for a greater role in other research projects associated with ITER.

Those involved in the decision-making all say they would prefer a full international programme, but stress that talks cannot continue indefinitely. One official, who asked not to be named, points out that ITER currently has backing from the highest political level of the union. “But in another year nobody can say what the level of support will be,” the official adds.