What is the first action to take when reacting to overhead flares without any warning?

When reacting to overhead flares without any warning, assuming a prone position is vital because it minimizes your silhouette against the sky and reduces visibility to potential threats. This position allows for greater concealment while also giving you a stable posture that is beneficial for assessing your surroundings. By getting low to the ground, you are less likely to be targeted and can remain hidden as you evaluate the situation or prepare for further actions.

The other options may be situationally appropriate, but they do not prioritize immediate safety in the same way. For instance, seeking cover could be a reasonable step, but without knowing the location of threats or the landscape, doing so might expose you unnecessarily. Looking for a safe escape route is important as part of broader situational awareness, but it's crucial to be low and hidden before moving to avoid detection. Alerting team members can enhance group safety, but it wouldn't be the first instinct when overhead flares signal an immediate tactical consideration.