A couple of the NCO Command Squad skills seem a bit problematic for underground combat.

Smoke Mortars represent "a special Artillery Strike that uses smoke shells instead of explosives" (Operation Cerebus, pg. 10).

Ammo Dump represents "an airdrop of ammo to a friendly unit" (Operation Cerebus, pg. 11).

Based on the fluff, it seems like neither of these skills should be usable underground.  However, I don't see anything in the rules which would prevent their use.

How would you folks handle their use in underground scenarios?

Yeah, from the fluff you shouldn't be able to use those, but from the rules themselves there's nothing really preventing it. I'd ignore the fluff and just use the damn things, it's more fun this way.

I'd go the opposite and say they shou;dn't be used, after all smoke is a special 'artillery strike' and artillery strike is in the rules and as they can't be used inside buildings, they certainly can't be used underground.

yeah, but you're going with the fluff, not the rules. Smoke Mortar is Smoke Mortar, it's got nothing to do with Artillery Strike, and nor does Ammo Dump. If it were called something like "Artillery Strike: Smoke Mortar" you could have a case. But as it is, disallowing their use underground is a straight-up house rule.

from one of the printouts(one of the quick reference sheets) i have of NCO command squad abilities, its has:

Smoke Mortars (skill) once per game immediately target 1 space in LOS (not into a structure) with this Artillery Strike (italics not mine)

That would seem to say to me, that it is an artillery strike, therefore not allowed in structures…and since underground is essentially another type of structure, sewers or subway restricted. (in addition to common sense….but we are looking for rule clarification)

as for Ammo Dump, ya, its got nothing that would be restrictive to underground/in structures, so teleport those supplies in! :)

Humm, good point. If the rules refer to Smoke Mortar as "a special Artillery Strike" then I can accept that the same restrictions apply.

No justification for Ammo Dump, though. I guess they just drop those through the gutters.