How did international law before World War Il determine the obligations of neutral states?

[Revonaire]

Hello!
(I apologize if this post is unrelated, please inform me to delete if you find it inappropriate)
Recently reading about law of neutrality, I'm curious if pre-war international law placed restrictions on intelligence cooperation between neutral and belligerent states. Went through Hague conventions on Neutral Powers in land & Naval war (both adopted in 1907) , didn't see anything related.
The definition of neutrality seemed to be less strict then than it was after 1949 (Regarding this https://casebook.icrc.org/glossary/neutral-state )?

Any help would be greatly appreciated!

[gebhk]

I would love to know the answer to this one too. From the odd contacts I have had with the subject, the obligations (or at least their totality) tended to vary on a case-by-case basis - such as the size and composition of the armed forces allowed, for example. But I have never come across a baseline international standard or law.

[Revonaire]

Something that makes me wonder even more: as a rule, it seems that a neutral country cannot allow the presence of foreign troops/military base on its territory even in peacetime, and I'd like to know if there are any laws that explicitly mention this?

[gebhk]

That too is a good question - albeit clearly during the war a number of neutrals did allow bases of combatant nations on their territories. I have come accross a number of cases (eg Denmark, Luxembourg) where defence measures taken in peacetime (such as disposition of forces, siting of prepared defences, etc) were aimed in equal measure (and were seen to be made) against both sides of any potential conflict. However, again, I am not at all sure whether this was due to some international 'rules' or just case by case politics.