Even if they file a lawsuit there is no possibility of recovering the hacked funds, because it is in North Korea.But atleast these things are now getting the attention from government which may become a reason for more regulations in crypto currencies on several countries.
If you read the documents, it didn't mentioned that the hacked funds are in North Korean hands, in fact, they
(1) identified a US email based
(2) when cyber threat actors tries to convert the stolen funds
(a transaction ID beginning with 6918d31f), the exchange didn't proceed, perhaps the coins has been trailed and on the blacklist of exchange already
(3) they move to other exchange, but since it is blacklisted already, been flagged so no cash out happened.
Which means that the funds are sitting to those exchange right now and the US authorities did file this lawsuit to claim those and give it back to the right owners. And you have to understand that this case is not against North Korean hackers directly, but "
in rem" - meaning lawsuit on the property itself, in this case the stolen cryptocurrency.
@tomahawk9 - yes, even the exchange are not being mentioned, but as crypto enthusiast, and who have been following North Korean modus, I'm sure that it is indeed Monero here being used for crypto jacking.