TOYAKO, Hokkaido — On July 1, 1968, world leaders signed the Nuclear Nonproliferation Treaty, or NPT, in which nonnuclear weapons states agreed to never produce or acquire such arms while countries possessing them agreed to eventually scrap their arsenals.

Four decades later, nuclear weapons remain and the goal of the NPT, which comes up for review in 2010, shows no sign of being fulfilled. The last NPT review conference, in 2005, was widely regarded as a failure.

But even as the Group of Eight leaders in Toyako, Hokkaido, announced strong support for the treaty, antinuclear activists raised questions as to why the G8 is simultaneously saying it supports preventing the proliferation of nuclear weapons and their materials, yet encouraging, in separate statements, a worldwide expansion of nuclear power generation.