"Iran is dangerous," Bush said after a White House meeting with Italian President Giorgio Napolitano. "We believe Iran had a secret military weapons program, and Iran must explain to the world why they had such a program."
Bush's comments came after Iranian President Mahmoud Ahmadinejad said that it was "a step forward" that U.S. intelligence agencies had concluded that Tehran stopped developing its nuclear weapons program four years ago.
Ahmadinejad told reporters that an "entirely different" situation between the United States and Iran could be created if more steps like the intelligence report followed.
"We consider this measure by the U.S. government a positive step. It is a step forward," Ahmadinejad said.
"If one or two other steps are taken, the issues we have in front of us will be entirely different and will lose their complexity, and the way will be open for the resolution of basic issues in the region and in dealings between the two sides," he said.
Iran has said its nuclear program is peaceful, but until last week, the United States and Western allies had countered that Iran was hiding plans for a bomb.
Russia has been developing an energy module on the basis of the megawatt-class nuclear power plant since 2010. The spaceship needs neither sunlight nor solar batteries