War and secured countries

Quick question about war : since I've a secured leader country and an unsecured slave country : if the slave was attacked, could the leader offensive units enter the slave and fight the attackers, despite the leader country not being at war with the attackers? Thank in advance!

No the leader country has to be at war also.
But, the leader country will help with defense, if it has interceptor/helicopter wings set up and as long as both countries are in the same federation.

Are you sure? In peacetime you can transfer offensive weapons to your slaves. Is this really blocked during war???

The leader country can transfer all the weapons it wants.
The leader land units cannot fight the attackers without it being in the war.

Allright, so our Rotor friend could actually just dismantle his units, transfer the weapons to the slave and recreate them there. This is kind of pointless,but wth.

Well, I this is pretty realistic. It's like the cold war - the superpowers rarely had their own soldiers involved, but they would give arms to their pawns and control things that way, so they didn't have to be "at war."

Generally it's not a good strategy to hold weapons in your main country anyway, unless you have no slave and you need some weapons to take your first C3.

See, you dont need them for defence, use your slave for taking further C3s or proper wars. This way you can maximise your mains income (no cost of maintaining military) and have the max amount of pop for corps. Of course, buying ammo and keeping that in a main is a good thing, and you can transfer it to your war slaves anytime it's needed.