Edward Snowden says he went to work for a defense contractor so he could inform the American public about the government's secret surveillance of telephone and Internet conversations. Having fled from Hong Kong, he's still thought to be in the Moscow airport. Over the weekend, London's Guardian newspaper and Der Spiegel in Germany published new revelations that the US has spied on allies as well as enemies. Angry leaders in Europe say that could scuttle a trade deal between the US and the European Union — the biggest ever negotiated. Does the US keep more secrets than it needs to for national security? Should whistle-blowers be prosecuted or protected?