A while back I wrote a blurb about how blocks of IPv4 address spaces are becoming a valuable commodity
The “class A” network for 137.*.*.* was originally allocated to the 754th Electronic Systems Group, which is located at an Air Force Base in Montgomery Alabama in charge of pretty much everything the Air Force does with computers.
I mentioned in passing a spike in hacking attempts following Heartbleed. One of the symptoms is signups for accounts with random strings of letters@hotmail that bounce because Hotmail has already blocked their account.
The same group also controls 188.8.131.52/8. Keep in mind the US military has an entirely separate Internet called Milnet that is isolated from the public Internet
As it turns out, two different non-human intruders from China are living inside “reassigned” IP blocks that were previously controlled by the USAF. That very likely opens holes in firewalls where people just said “if the IP address starts with 137. let them right in – it’s the US Military – you can trust them!