During the Cold War, America developed a huge nuclear arsenal capable of destroying the Soviet Union. But concern about collateral damage and the fear of retaliation prevented these weapons ever being used. Now there is a push to develop mini-nukes which can be used on the battlefield. "People talk in elaborate, glorifying terms about this fantastic weapon that you can just use without any real concern about collateral damage", complains Hans Kristensen from the Federation of American Scientists. But according to General Habiger, even with 'bunker busting' nukes, where the blast is contained underground: "You are still going to get radioactive material which is going to get into the atmosphere and kill." Despite Republican pressure, Congress has so far rejected demands to approve bunker-busters. But it has lifted a ban on the development of mini-nukes and agreed to modernise and completely replace America's existing nuclear arsenal. As Habiger states: "What we are doing is developing a nuclear weapon that is more viable, more attractive to use."