The Blok 2BL was a rocket stage, a member of Blok L family, used as an upper stage on some versions of the Molniya-M carrier rocket. It was used as a fourth stage to launch the Oko missile early warning defence spacecraft.[1]


  1. ^ "US-K (73D6)". Gunther's Space Page. 2012-03-08. Retrieved 2012-04-21.