This is an insightful question. I totally agree that trust is something foundational to all human relationships. Moreover, I would love to say that we can trust all people and that the international community can trust each other. However, I would not say that at all. Let me explain.
First, while I do believe that there can be a certain level of trust in society, in the final analysis people are inherently selfish and will do what is in their best interest. What is true with people is especially true with nations. National interest trumps nearly all things, if not all things.
Second, all we need to do is look at history to be able to prove that nations have always fought each other. Even as we become more educated and enlightened, wars do not cease. Even a hundred years ago people were speaking of the brotherhood of the world, but look what happened - World War I and World War II.
In light of these points, it is wise not to trust too much. It is wiser to cover yourself in a broken world.