Naysayers cite potential for accidents and weapons proliferation from Russian mobile power stations.
To Washington's consternation, Russia is building floating nuclear stations that are meant to bring cheap energy to remote areas - but are potential waterborne "Chernobyls" that easily could be raided by terrorists.
The units would serve as huge atomic batteries moored off coastlines. Each would be able to provide enough power for a town of 50,000. Construction has begun for components of the first mobile station, which is due to start up within four years in Pevek, 600 miles west of Alaska.
If successful, it would be followed by half a dozen more in Russia's far east and extreme north - and possibly others in Indonesia and the Philippines.
This unnerves Russian ecologists, who warn that the stations equipped with the same type of reactors as nuclear-powered icebreakers are accident-prone. A leak during a monsoon or earthquake, or near an Arctic ice floe, could leak radiation across the planet.
Just as dangerous, they say, is the risk of nuclear proliferation to politically unstable or rogue countries. It would be difficult to safeguard the units. And the uranium to be used is 60 percent enriched - which could be reprocessed to build bombs.
"These floating stations would be absolutely dangerous from the ecological point of view," says Andrei Yablokov, one of Russia's leading environmentalists. "The project does not envisage how to guard these stations against terrorists. They could spread nuclear weapons throughout the world, changing the geopolitical picture."
The project is illegal as well as hazardous, he says. He cites four Russian federal laws that have been violated because the work is proceeding without requisite approval by independent environmental experts.