I have been researching these topics for the last 6-7 years.

The triangles you wrote of, Silverblade are all over the place in the united states. There are several sources stating these craft are built in the United States. And because there have been many ongoing treaties with the well known extraterrestrial tyrants (commonly known under greys, reptilians etc.) for the last 60+ years, many of the underground corporations (who pretend they're government) who work in conjunction with these extraterrestrials and their agendas, now own this kind of technology that is completly out of the scope of the public.
Regarding the purpose of the triangle craft: from all the data I could gather it's a serveillance and abduction/personal transportation scoutcraft.
But there are have also been reports of bigger ones, in fact some of them so big they'd fill the entire sky of the observe if they were low enough. The reason they are only visible at night most of the time is because they block out the stars, and at daytime they are only visible in the infra-red light spectrum and they have been observed using 3rd gen night vision devices.

People are now discussing these topics, taboo'd by The System, in many forums, which means that the general state of ignorance is finally breaking down.

If you like passive psychic arts by the way, try remote viewing, it's a lot of fun and everybody can do it. Most of you will be astounded that you can actually gather real data from anywhere/anytime in the space & time continuum, just with your mind. This is a great training site for remote viewing:  http://www.dojopsi.com/tkr/ and forum: http://www.dojopsi.info/forum/index.php
In fact the CIA has admitted of using Remote Viewing to spy on the Russians in the cold war.

kind regards,

Paul