The manual doesnt explain what this represents, but I assume that this is the internal economy that the country use for troops and war. The manual says that when you're in war, it will raise.
However, I think this should be something manual, not automatic, because if you want to be the attacker you must first build enough units and then attack, dont declare the war, wait to have enough PPs and then you have 3/4 parts of your country destroyed.
I know these changes cannot be instant, or there is a maximum. Maybe Turkey cannot use more than 70% of his internal economy to PPs, and if you change it from 10% to 50% it must took 6 months to do the change.
Please, allow change the war economy in order to prepare an attack.... or a defense... if you're surrounded of allies and you're pro-axis....