The scariest thing about Hamas is they aren't clear which river or sea they're referring to so they technically have grounds to invade almost every country on earth.
In countries like Mali where there is no sea, this could mean simultaneous invasions of Guinea or Senegal to establish a river-sea corridor.
Is Israel the goal or are they just the first maritime country Hamas has encountered?
From every river to every sea Palestinians will be free. They can't be free somewhere there isn't a river or sea though so for now the moon is off limits. Maybe someday
Mars however has clear evidence of ancient riverbeds and oceans. All Hamas has to do is hijack a spaceship and suddenly we're facing interplanetary glider attacks.
I believe they refer to the landmass between the river Jordan to the Sea of Tranquility on the moon. Depending on where the moon is at any given time, Palestine will either be the smallest or largest country on the planet.