[Goose]

It strikes me that 3 days truce could be used to move troops through a vulnerable area to a new front.

True, but that applies to both sides. In theory Ukraine could "easily" swap out some of the troops fighting in the Donbas. They could also be re-supplied with impunity. However, given how poorly the previous "truce" proclaimed by Putin was observed IMO this 3 day one will be no different. If either side sees juicy targets of opportunity they will be attacked.

[Goose]

It strikes me that 3 days truce could be used to move troops through a vulnerable area to a new front.

True, but that applies to both sides. In theory Ukraine could "easily" swap out some of the troops fighting in the Donbas. They could also be re-supplied with impunity. However, given how poorly the previous "truce" proclaimed by Putin was observed IMO this 3 day one will be no different. If either side sees juicy targets of opportunity they will be attacked.