encirclement

noun

1. (countable, uncountable)The act of encircling or the state of being encircled
2. (countable, uncountable)The isolation of a target by the formation of a blockade around it

   “Not only did it give the Russians an abiding fear of encirclement, whether by nomadic hordes or by nuclear-missile sites, but it also launched them on their relentless drive eastwards and southwards into Asia, and eventually collision with the British in India.”