Or maybe a pop-up schould appear saying :
air fleet based in neutral Spain is able to intercept Italian air fleet attacking Gibraltar,
do you want to intercept?
yes= 50% chance the Axis invade Spain, or Spain kicks the allies out.
no= nothing changes
And I would also like to see neutrals asking for allied assistance if threatened by the Axis, and the effect that the giving or not giving of this assistance has on that neutral's leaning.
In general I would like to see a lot of possibilities to influence neutrals and also more phases between neutral and war declaration.
for example:
-Non-aggression pacts
-economical cooperation pacts
-As you said, allow troops to move through neutral territory without joining the war.
-And other...
And different kind of alliances incorporated in the game :
-commonwealth alliances
-military alliances(like NATO, where the invasion one member automatically leads to a war declaration from all members)
-Mutual assistance pacts
-alliances where one country is the dominion of the other(UK-Canada)
-And other...
What about dictatorships like Germany? Should they have the same limitations to promising territory to other countries or not? After all, they don't have a real democratic parliament.