Text on card:
Select your planet. You can move to
3 ground units to another planet, as well
under your control. Between the two
planets should be a path that does not
containing an enemy fleet.
Play. As action.
The actual text of the card is:
"You may move up to 3 Ground Forces from a single planet you control to another planet you control. You must be able to trace a route with no enemy ships between these two planets."
I think that makes it more clear that a ship above either of the planets is in the way. It is probably best, as a rule, to use the actual text of Action Cards.