encirclement

From encircle +‎ -ment.

encirclement (countable and uncountable, plural encirclements)

1. The act of encircling or the state of being encircled
2. (military) The isolation of a target by the formation of a blockade around it
   • 1990, Peter Hopkirk, The Great Game, Folio Society 2010, p. 9:

     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.