Forts were framed for defence against land or sea forces, but useless against an air attack.

建筑城堡是为了防御陆海军入侵，但对于空中打击就无效了。

youdao

This paper proposes an improved Statistical Hitting Set attack (SHS-attack) based on MIX anonymity technique and a defence strategy based on dummy packets to counter against this attack.

基于MIX匿名系统模型，提出一种改进的统计命中集攻击算法，并在该算法的基础上给出基于填充包的防御策略。

youdao

But it is also vital that progress be made towards the construction of an effective global defence against missile attack.

CENTERFORSECURITYPOLICY: 'Courage'