Do you think aliens in ufos have visited Earth? (And all things UFO)

I have no doubt aliens are real. I have no doubt they have visited earth. I wouldn't be a bit surprised if some are living among us. I just don't think our Gov't is smart enough to hide tons of evidence and suppress the numerous witnessess for this long. and it's not like they only visit the USA... if gov't's have proof, some third world country like North Korea wouldn't suppress that info , they world be trying to use the tech