All human beings have an innate desire to overcome suffering, to find happiness. Training the mind to think differently, through meditation, is one important way to avoid suffering and be happy.
I believe that the basic nature of human beings is gentle and compassionate. It is therefore in our own interest to encourage that nature, to make it live within us, to leave room for it to develop. If on the contrary we use violence, it is as if we voluntarily obstruct the positive side of human nature and prevent its evolution.
In some cases, lack of full knowledge or holistic view, that is also part of the problem. But mainly lack of moral principle. So long you have this genuine sort of concern, well being of other. That's the foundation of moral principle.
If the situation was such that there was only one learned lama or genuine practitioner alive, a person whose death would cause the whole of Tibet to lose all hope of keeping its Buddhist way of life, then it is conceivable that in order to protect that one person it might be justified for one or 10 enemies to be eliminated if there was no other way.
One has to try to develop one's inner feelings, which can be done simply by training one's mind. This is a priceless human asset and one you don't have to pay income tax on!
Although under particular circumstances, the violence method - any method - can be justified, nevertheless once you commit violence, then counterviolence will be returned.
The reality today is that we are all interdependent and have to co-exist on this small planet. Therefore, the only sensible and intelligent way of resolving differences and clashes of interests, whether between individuals or nations, is through dialogue.