This is an interesting question.
I think you can have benevolent political leaders, but a leader is only a small part of the machinery which operates a country. There are business interests, ideologies and other factors which dictate what a leader is capable of doing.
The following statement is from Hermann Göring after he was captured at the end of WWII:
Naturally, the common people don't want war; neither in Russia nor in England nor in America, nor for that matter in Germany. That is understood. But, after all, it is the leaders of the country who determine the policy and it is always a simple matter to drag the people along, whether it is a democracy or a fascist dictatorship or a Parliament or a Communist dictatorship. ...voice or no voice, the people can always be brought to the bidding of the leaders. That is easy. All you have to do is to tell them they are being attacked, and denounce the pacifists for lack of patriotism and exposing the country to danger. It works the same way in any country.
That last statement is unfortunately true. You just need to inspire some patriotism in the population and condemn the critics for being unpatriotic and conspiring against the "interests of the people".
I see this kind of "patriotism" with PRC nationals much of the time. They're quite willing to condone violence and brutal violence against those who would "split China". Splitting China is a heresy that must be crushed by any means including murder. They might think Taiwan is a part of China, but they have no problems killing the inhabitants of the island if it means China secures what belongs to it.
They say to me, "Doesn't a country have a right to defend itself?"
Sure, to a certain extent, but that idea of "self-defence" can easily be warped and used to support "pre-emptive strikes" against an "axis of evil" or whatever, when in reality it is business interests behind the attacks.