Supply from a port

[havoc1371]

I have Japanese SF units in Hawaii and control the both the outer ports with the southern outer port at a strength of 5. My opponent lined the coast next to my units with ships. Despite having the port with 5 points that isn't being reduced, my supply is "1" in the hex next to the port and "0" elsewhere, and both SF's are being reduced by attrition. Why?

[The Land]

ps. Despite having the port with 5 points that isn't being reduced, my supply is "1" in the hex next to the port and "0" elsewhere, and both SF's are being reduced by attrition. Why?

Ports give no supply if there is an adjacent enemy naval unit. This effect is different from the port being reduced, which requires 2 adjacent units.

[BillRunacre]

Essentially, enemy naval units are preventing supplies reaching your troops via sea. The navy and/or airforce are going to be needed to rectify the situation!