The United States on Sunday said it may use nuclear weapons if the country comes under biological attacks, according to a repot in Dawn.
Secretary of State Hillary Clinton said on Sunday the US could not rule out using nuclear weapons, saying in that case "all bets are off."
Both Hillary and Defence Secretary Robert Gates said in television interviews that Iran and North Korea represented exceptions to the limits on a US nuclear response, the Pakistani newspaper said, qouting agency reports.
"If we can prove that a biological attack originated in a country that attacked us, then all bets are off," she said in an interview with CBS's Face The Nation.
Hillary was referring to a new US nuclear policy unveiled last week that restricted the use of atomic weapons against non-nuclear states that complied with the Nuclear Non-Proliferation Treaty (NPT).
Asked why Iran and North Korea were considered exceptions, Gates said: "Well, because they're not in compliance with the nuclear non-proliferation treaty. So for them, all bets are off. All the options are on table."