Iran states that the purpose of its nuclear program is the generation of power and that any other use would be a violation of the Nuclear Non-Proliferation Treaty, of which it is a signatory, as well as being against Islamic religious principles. Iran claims that nuclear power is necessary for a booming population and rapidly industrialising nation. It points to the fact that Iran's population has more than doubled in 20 years, the country regularly imports gasoline and electricity, and that burning fossil fuel in large amounts harms Iran's environment drastically. Additionally, Iran questions why it shouldn't be allowed to diversify its sources of energy, especially when there are fears of its oil fields eventually being depleted. It continues to argue that its valuable oil should be used for high value products and export, not simple electricity generation. Furthermore, Iran argues that nuclear power makes fairly good economic sense. Building reactors is expensive, but subsequent operating costs are low and stable, and increasingly competitive as fossil-fuel prices rise. Iran also raises funding questions, claiming that developing the excess capacity in its oil industry would cost it $40 billion, not to speak of paying for the power plants. Harnessing nuclear power costs a fraction of this, considering Iran has abundant supplies of accessible uranium ore. These claims have been echoed by Scott Ritter, the former UN weapons inspector in Iraq. Roger Stern, of Johns Hopkins Department of Geography and Environmental Engineering, agrees "Iran's claims to need nuclear power could be genuine".