UFO or legit air craft?

About 10 years ago when I was around the age of 13/14, I looked up into the sky at about 10PM one summers eve and saw three triangular lights which were green and there was no sound was present. I'm not actually sure what it was. There was an RAF base near to me then and so I thought it may of been a B-2 stealth bomber but I wasn't aware of these type of air crafts being at this base at that time, I know they had Tornado's, Harriers and C-2 cargo planes (I Think), MD Phantom's and believe it or not, I was actually told that they had something to do with the Eurofighter Typhoon back then!

Any ideas?

They were probobly UFOs. Ive seen a steath bomber and they are very loud, you would know if you saw a B-2.