Yes, I do believe in alien intervention; absolutely, and I know there is plenty of evidence, but it is 'classified' information that no one can access except a very few selected people.
There is absolutely no evidence of alien visitation. There are lots of "Unidentified Flying Objects", but most have very terrestrial explanations. So, my view is, yes, there are plenty of "UFOs", but they certainly are not aliens.
Yes, I believe they exist. In fact lately I've been thinking I've been alien abducted and dropped onto some planet other than earth. Or maybe our lawmakers were alien abducted and replaced with aliens who want our country to fail. Hummmm.....