If you do damage in multiple lands with a single instructions, does the damage happen simultaneously? Against Russia level 2+, if one of those lands is Isolated, can you attempt to Push an Isolated Explorer and thus destroy it?

If you do damage in multiple lands with a single instructions, does the damage happen simultaneously? Against Russia level 2+, if one of those lands is Isolated, can you attempt to Push an Isolated Explorer and thus destroy it?

Damage instructions are simultaneous in all the lands where they apply. Russia's Sense for Impending Disaster effect requires you to Push an Explorer if you can (and generate 1 Fear); you cannot pick an Isolated Explorer as the one to Push if you have another choice.
This applies to any effect that deals damage in multiple lands at once.