I never said it is only possible for life to breathe oxygen, but any race capable of getting here would have some form of data on this planet unless they were incredibly desperate, so they would bring some sort of self-contained atmospheres inside of a suit that they would be wearing.Or they would use an army of robots, whatever floats your boat.
we have the technology to stop robots, if they had suits a bullet could pierce it and suffocate them, it would be super easy. we won't be invaded.
ALL LIFE IS PART OF ONE, WE WILL JOIN TOGETHER INTO ONE BIG BLOB CALLED THE UNIVERSE.
So wise one, how will we stop an army of robots without frying all of our own technology? Also, the thing is the suits would also be armor.
Here, let me pull a hopeless situation out of my ass and rub it into some guys face, asking "how, how will we win this un-winnable battle?"What if they are able to drop pesticides onto the planet, that essentially only kills mammals or something. Then what, how will we stop them?
For those of of you who don't know this, they sent a space probe (that is currently on the edge of our galaxy) that has music, poetry, 27 languages of earth, art, video, and some a metallicly sketched picture of what a human and a woman look like.
I bet you also believe there is a planet out there full of furries.