Assume that there is head of state that is elected in elections that are fully recognized in his/her country and that is at least partially recognized as a elected head of state by other countries and to whom (notwithstanding previous disputes) the other countries have conferred the full diplomatic privileges that are associated with his/her status as a legitimate head of state.
Assume that this head of state takes decision to perform act of war against the other sovereign country and this act of war therefore violates the International law.
Assume that other countries issue financial, economic personal sanctions against some persons of the country which performed acts of war.
My question is - why there are never the sanctions against this head of state (decision maker) but why the sanctions are directed only towards the lesser functionaries? I have heard that the his/her status of diplomat provides the full immunity against such sanctions, but - I can not understand - whether or not the diplomatic immunity and privileges are preserved when his/her orders violates the International law?
And in what cases (what laws additionally should be breached) the head of state is subject not only to the personal financial sanctions but he/she can be made captive (prisoner) and tried in the court or outright executed without trial?