UFO,s Who and Why

I am busy watching a program on UFOs and got me thinking . If they are aliens or advanced races and can fly through space and time they could probably wipe us out if they really want to . However when ever there is activity on nuclear bases there seems to suddenly be an upsurge of UFO sightings . Maybe its something from our future trying to get us to change course or its aliens who have already experienced nuclear war etc and are also trying to warn us against repeating what they have already lived through . Maybe its about time we changed our thinking and changed direction . Maybe these aliens or what ever have become peaceable people without the capabilities to destroy us and are just trying to stop us making the same mistake and scared of getting to close because when ever they have we have tried in every way to destroy them and fire on them . Maybe if our forces stopped firing on them and trying to destroy them just maybe they would feel safe enough to make themselves known to us .
After all there is a times past where they have landed and been seen by alot of people in situations where they didnt feel threatened and showed themselves . One I recall is a few years ago one landing in a school playground in zimbabwe . I know there have been others just cant recall at this moment .
Just maybe if we stopped being so hostile when they are sited and stopped sending fighter jets etc to intercept just maybe they might feel confident enough to show themselves to people on earth .
Could it be that our governments are hiding crashed craft from us and maybe even living aliens hence another reason their scared of making themselves known . Just maybe they fear us and so are keeping their distance . After all if their that advanced that they have conquered space travel etc and have the weaponary to destroy us why havnt they . Why are all our governments hell bent on the thought that their out to destroy us , when all the evidence shows the opposite .