Any negotiation has a limit.
Otherwise, war is irrelevant.

The finite mind tries to limit the infinite.

There are no walls at the edge of this universe...absence of gravity is the limit of space existence.

Nobody could rule this world merely by peace.

While you try to make peace on earth,
the inhabitants of heaven are still at war.

Like it or not, the governments of this world need to be well-prepared at the time when the alien races invade the earth. That will be the trigger. Nevertheless, the most dangerous thing will not be caused by the invaders, but by the ignorant opportunists amongst human who will start the last civil war.