Greenwald said that for the past six weeks he has carried around "for every second of everyday" a highly encrypted electronic copy of the secret documents leaked to him by Snowden – some 10,000 documents from the NSA. Greenwald said that he has other copies should anything happen to the one he carries around, and Snowden has previously said that other encrypted copies of the documents have been given to other journalists for safe keeping.
As for the concerns over whether Russian authorities could copy the documents Snowden is reportedly carrying with him – or if Chinese intelligence agents had done so already when he was in Hong Kong – Greenwald said such concerns underestimate Snowden's experience in the world of high-tech spycraft.
"This is a very sophisticated cyber operative," Greenwald said before referencing a report from The New York Times which said Snowden had been especially trained by the NSA to be an offensive cyber attacker. "This is somebody who completely knows what he's doing in terms of how to store material securely and what techniques are used by governments around the world, like the NSA, in order to gain access to places they don't have authority to access."
Snowden has been charged in the U.S. with espionage.
ABC News' Lee Ferran contributed to this report.