Yeah as Dewirix wrote, the Ai has a problem and wants to supply every port you own. By directly controlling you can use your convoys better and more efficiently. And about your thinking of opening another front in Europe, maybe you should wait for an allied landing in Europe. After all, now that the US is at war, the invasion threat is almost imminent in Europe so you should watch the overall allied progress and try to help, where the help is really needed. Join the European invasion force, if you think it's a respectable one. Otherwise, maybe you should consider a change of theatre, you could wreak havoc among the Japanese.