i think in order to land a plane into a dutch territory you have to controll it from the beginning of the turn.
that’s why dutch territory income it’s free and it’s not under controll of any allied nation in order to land a plane into a dutch territory you have to land a land unit than controll it and on the next turn you can land plane.
Only if you controll the dutch territory you collect the income and you can land airforce in it.
The friendship between allies and dutch only result in a non state of war if the british forces take controll of the dutch territores, instead if japan take controll of dutch territories there is an immediate state of war.
this is my interpretation let’s wait krieghund