As news of satellite images showing a Russian build up of troops across from Ukraine comes out, I can see one reason why we haven't been sharing detailed intelligence about the Russians.
Sharing intelligence with the Ukrainians on Russian troop deployments threatening an invasion seemed like a no-brainer to me, but after seeing some of the photos (here, here, and here), I can understand one reason for not wanting to do so--we don't want nervous Ukrainians thinking their small military needs to launch a preemptive air and missile attack to do some damage while they can.
One, I do not believe that the Russians are incapable of hiding deployments if they wanted to. I think the Russians clearly want their troop build up seen by satellites.
Heck, I wonder if we know they are real and not plywood or inflatable?
Aircraft lined up along an airfield are even more bizarre. Really? Lined up wing tip to wing tip to be attacked and not in shelters or even just dispersed?
The latter is what really gets me thinking that the last thing we want Ukrainians--understandably worried about being invaded (again)--to do is use that information to launch a preemptive attack on Russian airfields and units deployed close to Ukraine. Especially if we judge the Russians are not serious about invasion despite the very real deployments and capabilities to move into Ukraine on short notice.
And I'll say again that while the Russians could move into Ukraine with this force, I think it is insufficient to fight a real war without losing the aura of skill that the Spetsnaz-led offensive in Crimea created.
But we can't orchestrate both sides. We'd like Ukrainians to be able to defend against a Ukrainian invasion. But perhaps we don't think Russia will invade and we don't want nervous Ukrainians to strike first in the belief that this is the only way to disrupt a looming Russian attack.
But we don't know if Russian intentions will change overnight, letting them use their capabilities. And we don't know if Ukrainians will use a new capability (based on detailed intelligence) to empower a change of intentions from defense to offense overnight.