Wikileaks, how come US gov still leaking to them?

Wikileaks going in the news lately. How come they keep getting more and more documents? This shows that the US government doesn't do much to protect their informations. They have moles here and there. From the way I see it, they don't seem to be doing anything. Something leaked, did they catch the guy who leaked the info? The American need to buck up and protect their data. All the security to protect their properties against bombing but nothing been done for info leak.