I came across this posting that outlined 12 government documents that shows that the U.S. government does take UFO events very seriously.
There are some surprises for me in looking over that article. I personally had not heard of the March 4, 1988 U.S. Coast Guard encounter. That incident took place near Eastland, Ohio.
Visit that website and read the information there. The link is below.
image is off Google search for UFO pictures.