Most other wars there are understandable reasons on both sides, and it's easy to imagine people in the military or with the right security clearance who are motivated to leak something because they genuinely believe the US or the West is the bad guy.
But who has access to this stuff who wants to help Russia and harm Ukraine? When this is not a war where people are siding with the Russians. I just... it's so hard to see where that Venn diagram overlaps.
Do the Russians have spies in the US government that can access this stuff? How have our security processes not caught that?
Or did Russian spies pay someone with clearance to get these? Why did that person go along with it? Did they know they were Russian spies or did they think they were helping good guys, like Ukrainian spies? (Something like that was depicted in the TV show The Americans.)
Most leaks it's pretty easy to understand how somebody with access to information would have had motivations. This one, it seems very non-obvious.