The Collaborative International Dictionary of English v.0.48:

Counterstroke \Coun"ter*stroke`\ (-str?k`), n.
   A stroke or blow in return. --Spenser.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "counterstroke":
   backfire, boomerang, comeback, counter, counterattack,
   counterblast, counterblow, counterfire, counterinsurgency,
   countermeasure, counterrevolution, counterstep, defense, exchange,
   give-and-take, interchange, reciprocation, recoil, reply,
   retaliation, retort, return