One day after issuing a formal demand for WikiLeaks to hand over any and all classified military documents to the Pentagon -- DOD officials remain concerned over what has already been leaked, the danger it could put both U.S. forces and Afghan informants in, and maybe more, what information the website might be holding onto.

"Everything they claim to have and have yet to publish is a concern, because we don't know what it is and how damaging it could be to the armed forces," Pentagon spokesman Geoff Morrell told Fox News exclusively on Friday.

He added, "That's why we are trying to compel them to hand back over to us all that was stolen from us and they have published or threatened to publish."

Further complicating efforts for U.S. officials, late Friday Fox News confirmed that a Swedish internet company linked to the file-sharing hub, The Pirate Bay, is helping WikiLeaks release classified documents from servers in a basement in the Stockholm suburb of Solna. Apparently Swedish authorities know about the servers, but so far have not tried to shut them down.

The Pentagon appears primarily interested in blocking the release or another fifteen thousand Afghanistan war-related documents WikiLeaks claims to have withheld until now.

Adding to that concern - the website recently posted a massive, encrypted file labeled, "Insurance" which is twenty times larger than the original leak.

So could that file be the missing fifteen thousand cables? Not likely according to Morrell.

"I believe that is different than this reported insurance file that they hung on their website. I don't know what that is, and I couldn't tell you if there's anybody else in the U.S. government who has determined what that is," he told Fox News on Friday.

Another possibility is that it could be many as 260,000 classified State Department cables the government believes may have been accessed by Private First Class Bradley Manning - someone DOD officials have labeled as a "person of interest" in their on-going investigation.

Manning, a former Army intelligence analyst, has already been charged with leaking classified video of a 2007 incident involving an apache helicopter attack in Baghdad.

State Department spokesman P.J. Crowley told reporters, "To the extent that we can indentify documents that are ours that perhaps have migrated from government networks out, we are actively reviewing those cables to determine and assess the potential damage to our national security."

On Thursday Morrell demanded that WikiLeaks, "Return immediately to the U.S. government all versions of documents obtained directly or indirectly from the Department of Defense databases or records."

Morrell told reporters, "We are asking them to do the right thing. This is the appropriate course of action given the damage that has already been done, and we hope they will honor our demands and comply with our demands...if doing the right thing is not good enough for them, then we will figure out what other alternatives we have to compel them to do the right thing. Let me leave it at that."

Despite the sense of urgency displayed by DOD officials, WikiLeaks appeared unfazed, Tweeting, "Obnoxious Pentagon spokesperson issues formal threat against WikiLeaks: Destroy everything, or else" just hours after the Morrell press briefing.

WikiLeaks, an online whistle-blowing group, posted more than seventy thousand classified military reports from the Afghanistan war to its website last month, and the files have since been copied and downloaded by people all over the world.

Some officials have quietly suggested going on offense against WikiLeaks, but analysts insist it's not that easy.

James Carafano of the Heritage foundation tells Fox News, "Even if you took down their server, or blocked it or something, how do you know they just don't have it all on a disc and they walk over to another server and they just upload it there."