For the first time ever, the head of the UK's MI6 has made a public speech. Interesting enough, he claims that the biggest terror threat to the UK comes from abroad. Counterror officials in the US now believe the greatest threat comes from homegrown terrorists.So which is it? I can't help but think that both might be right. The UK has a much larger domestic spying capability. In the US, we don't spy on our own citizens. We can investigate them for criminal activity, but not spy. In the UK they can and do. So, they may have a better pulse on domestic threats and believe they are able to thwart those threats before they mature. We Yanks? Not so much. So, our biggest threat is homegrown. Their biggest threat comes from abroad. It's either that, or one of us is wrong. In which case serious resources are being wasted and our security is at risk.