Scpetics dont have a leg to stand on

After reading several of the major UFO cases:

The 1942 'Battle of Los Angeles
Betty and Barney Hill Abduction Case
Travis Walton Abduction Case
The Shag Harbour Incident

(Just to name a few)

how can one refute presents of alien/UFO ?, i can understand being extremely cautious not to back a case that mite be a hoax. BUT when you have Army anti-aircraft batteries firing nearly 2,000 rounds of 12 pound of high explosive shells in full view of hundreds of thousands of residents thats abit hard to pass off as swap gas or Venus. So scpetics please by all means deny the existence alien/UFO, BUT dont say its "cause there is just no hard proof".