The real purpose of those encounters is pure guessing game, although the officers seemed certain they involved the nuclear missiles storaged or tested on the areas of the claimed sightings. After the UFO visits the missiles on the area became strangely unoperable and shut down. The soldiers were ordered to stay quiet about the happenings.
UFO researcher and author Robert Hastings, who organized the conference, claims that more than 120 military personnel have told him about these various alleged encounters. Hastings himself believes that the aliens are keeping a close eye on the nuclear missile race, which began after World War II. The US Air Force did in fact study the UFO sightings from 1952-1969, however the the project (named Blue Book link)was ended due to insufficient data to back up the claims.
One of the witnesses stated that the US government had, in fact, been in close contact with the aliens. The attempts on communication had been futile -they, whoever they are, did not desire to explain themselves further for us mere earthlings. The retired officers did conclude that they do not know of the happenings of late, as they have been retired for quite some time.
The press conference was organized magically close to the appointment of UN ambassador to the aliens, which occurred last week.
The question of "have they arrived here or not" has been around since the 1950s, and most of us would clearly dismiss these ideas as pure fantasy, at its best. When imagining the size and scope of the known and unknown space, it is theoretically impossible to grasp on how other living, breathing humanoids could surpass the laws of physics and arrive here -light years away from home planet. Theories on warp drive aside, maybe the answers are beyond our comprehension at this point. The same way as the idea of a round earth circling the sun was once deemed heresy and a rocket to moon was fairytales.
These men, former military high-ups, clearly distinguished officers, put all their credibility and reputation on the line with these claims. Why would they do that on a whim?