That’s not true. It is impossible to get original documents out of storage at the archives. If he destroyed materials, he had to have done so before they went iinto the archives.
From the Wall St. Journal:
Another telling revelation concerns Mr. Berger's access to original, uncopied and uninventoried documents from the files of former NSC antiterror official Richard Clarke, among others. At the time Mr. Berger made his misdemeanor plea agreement, we were assured by then-federal prosecutor Noel Hillman that there was no evidence that Mr. Berger destroyed or intended to destroy any original documents. That was, strictly speaking, true. But during three of Mr. Berger's four visits to the Archives in 2002 and 2003, the former National Security Adviser did have access to original documents of which no adequate inventory existed or exists.
This seems relevant, given the concern that Mr. Berger's breaches of national security might have denied evidence to history of the Clinton Administration's approach to al Qaeda and the threat of terrorism. And yet the Justice Department clearly gave the impression that there was no danger that Mr. Berger abridged the historical record. We now know that this was not true. Mr. Berger was in a position to remove documents from Mr. Clarke's files, and thanks to lax security, breaches of protocol and undue deference on the part of Archives staff, we may never know whether Mr. Berger took documents other than the five he's admitted to removing.