reconnaissance
noun [ U ] military specialized uk/rɪˈkɒn.ɪ.səns/ us/rɪˈkɑː.nə.səns/ (UK informal recce); (US informal recon)
侦察
the process of getting information about enemy forces or positions by sending out small groups of soldiers or by using aircraft, etc.
Aerial reconnaissance of the enemy position showed they were ready to attack. 对敌人阵地进行的空中侦察显示，敌军已经做好了进攻的准备。