Aircraft are extremely expensive and AA has been brought in in those convoys, so it's a big risk. Attacking from the ground reduces the risk of casualties, but even then attacking a convoy isn't ideal as the amount of firepower concentrated guarantees a big and destructive encounter.
If they have the opportunity to wait for them to split off, they'll have better opportunity to take them out with minimal losses.
Doctor Foxx posted...
The demonizing of soy has a lot to do with xenophobic ideas.