It is impossible to preserve my friendship with people who are allegedly leaders when they are attacking their own people, shooting at them, using tanks and other forms of heavy weaponry.

This quote means that it is not possible to keep a friendship with people who are in authority when those people are using violence and weapons to hurt people in their own country. It means that no matter how close of a friend someone might be, if they are committing acts of violence against their own people, then it is not possible to maintain a friendship with them.