A trove of documents alleged to contain the names of thousands of ISIS fighters has caught the attention of U.S. intelligence officials, but they’re skeptical that the files will contain many new revelations about the terror group, three U.S. officials told The Daily Beast.

The files were obtained by Sky News and a Syrian newspaper, Zaman al-Wasl, and purport to detail the inner workings of ISIS’ recruitment operations. The U.S. officials said that they hadn’t yet obtained copies of the documents, but cautioned that doesn’t mean that similar documents haven’t been obtained and studied previously.

The documents also appear to be as much as three years old, which may make them less useful for planning military strikes than information about ISIS’s current status and operations.

U.S. military officials got their first look at the documents when they appeared online this week, two defense officials told The Daily Beast, and there were mixed assessments of their usefulness.

Within the military’s intelligence sector, officials scoured the names to determine who may still be alive and what the list tells them about the flow of foreign fighters to Syria.

So far, officials have concluded “a significant number” are dead, one of the defense officials explained to The Daily Beast.

Another U.S. official said the documents appeared to be old and that some of the information in them may have already been available from other public sources. That raised the question of whether the source of the documents, who has been identified in news reports as an ISIS defector, was peddling old, non-exclusive information.

But for those tasked with conducting strikes against the terror group, the list was not nearly as interesting, officials said, because it is three years old and offers little insight on where the U.S.-led coalition should hit next.

“We can’t do a whole lot with it” when it comes to crafting a strike plan, the official said.

There is, however, one issue both military intelligence and planners agree remains a mystery: why Germany, a U.S. ally, did not hand the list over sooner. German officials acknowledge publicly that they had at least some of the information being reported by news outlets. Two defense officials told The Daily Beast it’s not clear how long the Germans may have had it.

Determining why Germany did not hand over the list “is something everyone is interested in,” the defense official said.

Other indications that the documents may be outdated are found in the number of foreign fighters listed. Documents posted on the Zaman al-Wasl website list just 16 British foreign fighters out of a group of 1,736 yet hundreds of Britons are believed to have joined the ranks of ISIS.

Neither news organization has posted all the documents, but rather snippets and samples of what’s said to be a larger set. The documents on the Zaman al-Wasl website don’t list the fighters’ first or last names. It’s not clear whether that information was redacted by the website, or was absent in the original forms. Instead, the fighters are identified by their kunyas, or nommes de guerre.

The largest portion of foreign fighters on that list come from Saudi Arabia, totaling 485 people. In addition to the 16 Britons, the Zaman al-Wasl list also has 375 Tunisians, 140 Moroccans, 101 Egyptians, and 57 Turks; 35 Frenchmen, six Canadians, and four Americans are also listed.

Notably, the tally also includes eight Iranians. Most residents of the country are Shia, who are considered apostates by ISIS.

Forms that would-be ISIS fighters must fill out before joining also have a host of discrepancies, including in the way that nationalities are listed and how fighters give their dates of birth. Some list themselves as Canadians of Somali origin, for instance, while others say they’re simply Spaniards—though it’s not clear whether those who only list one nationality come from immigrant families or not.

Most give their dates of birth according to the Gregorian calendar year, while others use the Islamic calendar.

Experts who have reviewed the documents tell The Daily Beast that they also contain misspellings.

Even if these files turn out to be of limited use, in general, documents containing lists of names of ISIS fighters can be exceptionally helpful for intelligence purposes.

“They can help understand who recruited them, who they communicated with, their social networks—any trail they left,” Daveed Gartenstein-Ross, a terrorism expert and senior fellow with the Foundation for Defense of Democracies, told The Daily Beast. He compared the potential value of such information to the hacking of personnel files from the U.S. Office of Personnel Information, which has been attributed to Chinese spies and that experts say could provide a powerful guide for recruitment of intelligence agents and an insight on government operations.