Mud effect on combat

[abulbulian]

I've found both

[font="Courier New"]17. WEATHER AND SEASONS
Rain, snow and mud influence your movement speeds, combat capabilities and
logistical network. Aircraft never suffer penalties from any weather or seasonal state
because the 2-day turns allow enough space to find clear periods to perform combat
missions.[/font]

and a little further down

[font="Courier New"]17.4. EFFECTS OF A MUD HEX
Mud hexes slow down motorized and mechanized movement as well as the movement
type used for supply. Units that are in low supply in a non-mud turn, might well be
out of supply in mud turn. See the Landscape Movement Costs table (Section 4.1) to
compare the differences.[/font]


So the question is does mud actually effect combat or just movement (units and supply). Let's leave air out of this for now. If so, where in the rules is it?

Thanks