A key tell in the comments out of Europe regarding sanctions is the line "government-controlled Ukraine". It's been a demarcation point for how harsh sanctions will be.
It's now nearly 8 pm in Moscow and Putin has promised he will announce his decision on recognizing the independence of Donetsk and Luhansk today. The clock is ticking.
All indications point to him recognizing them as independent. That could set off a long chain of events and repercussions, with a big question being: What does Ukraine do to respond.
Much of that may depend on exactly which border Putin recognizes. It's mostly clear who controls what right now but there's some grey area on exactly what the lines are.
First of all, separatists control less than half of the Luhansk/Donetsk region. If Putin were to try to recognize the entire region as independent, it would be a major escalation. That would signal a Russian intention to push the Ukrainian military back and is the kind of thing that would likely mean full-scale war.
It's certainly not out of the question. A senior Duma member suggested Russia recognize the entire regions as independent, not just the separatist-controlled areas.
"It is clear that not within the borders within which the LPR and DPR currently exist, given the occupation by Ukrainian troops of a considerable part of the Donetsk and Luhansk regions. The administrative border could really be an option here."
Another grey area is around the exact line of the border of who controls what. During various agreements and ceasefires there have been different borders and rules with some strongly contested and some lightly contested.
Here's an illustration:
I don't think anyone wants war over 100 meters here or there but it might depend on how far Putin wants to push his luck.
There's also the question of what will be left vague. Putin isn't going to announce the exact lines of the border so we might simply be watching for indications on how strongly the lines are contested and see it left up to negotiations later.
All this to say that -- like in all conflicts -- there are ways this can easily get out of hand.