Sunnie

Yes, but how can we possibly know when we are capable of defending ourselves? Without having seen the threat we have no idea how advanced their technology may be. And perhaps there are aliens out there thinking the same of us. Consider the scenario of the human and the spider where we attack in order to defend. It is a possibility that the alien will be hostile but more likely only if it feels threatened. Let us keep trying to contact other lifeforms. Chances are we won't contact any significantly intelligent life for a very, very long time. And who knows at what level our technology will be by then.