Can ground units intercept/recon?

[Optimizer]

Can ground units do missions intended for air units? It would be great to have a recon squad able recon, an anti-aircraft gun able to intercept or a saboteur able to do precision bombing.

Moreover, can ground units use the sub flag to be invisible to most units?

[Admiral PJ]

To an extent YES,
if an air unit dosen't have IMMOBILE on (unchecked in the flag menu) it can move like a land unit, but it also moves over sea freely.
The problem is only the human player can use this, the AI dosen't seem to able to use these units properly.
It would be nice to have a saboteur/spy sabotage units, but it would be better just using a artillery type unit.

If you mean can ground units intercept air units for air defence.. I agree this could be good, maybe the aI can use it this way, but it would just be like an aeroplane still.