A bastion is a secure position used for defense against attack.

VOA: special.2009.08.17

Trotsky's Literature and Revolution is a brilliant book, an attack on many things and a defense of certain other things, but in particular and very painfully an attack on the formalists.

列夫，托洛斯基的文学与革命非常精彩，它攻击了许多当时的理论，同时也维护了一些，但是它特别猛烈地攻击了形式主义者。

耶鲁公开课 - 文学理论导论课程节选

Defense Minister Ahmed Vahidi says the Sejil 2 is intended to defend the country against outside attack.

VOA: standard.2009.12.18