分别tag SOV，tag USA 相互宣战就好

diplomatic_decisions = {
对美宣战= {
potential = {
tag = SOV
not = { has_country_flag = 对美宣战 }
}
allow = {
ENG = { war_with = GER }
}
effect = {
SOV = { country_event = 10086 }
set_country_flag = 对美宣战
}
ai_will_do = {
factor = 1
}
}
}
上面决议，下面事件我叫雷锋
country_event = {
id = 10086
is_triggered_only = yes
title = "进攻美国"
desc = "泥头车，绝绝子，给宁麻麻创死死！"
picture = "news_paper"
option = {
name = "确定"
national_unity = +1
SOV = {war = { target = USA} }
}
}