The fact that there has never been a major terrorist attack involving nuclear or other radioactive material should not blind us to the severity of the threat. There is evidence that terrorist groups have tried to acquire the material needed to construct a crude nuclear explosive device, or a dirty bomb.
从未有重大恐怖袭击涉及到核物质或放射性物质，这一事实不应该蒙蔽我们对该威胁的严重性的认识。证据表明，恐怖组织曾经试图获得制造原始核爆装置或脏弹的材料。