"To some it might seem that the devil is in the details of the February 2015 agreement, but, in my view, the heart of the impasse lies in the bigger picture: I believe that the primary reason the signatories to Minsk-2 keep locking horns over the fine print is that none of them—not Ukraine, not Russia, not the West—can be certain that their real minimal requirements for security will be met."

The Ukrainian army has made significant gains against pro-Russian separatists in recent weeks, forcing the rebels to retreat to pockets around Donetsk and Luhansk. Victory seems to be within the Ukrainian soldiers’ grasp, but can it be attained and will it last?