Here's a good story of a Buddhist reaction to a genocide in Lord Buddha's time.
"Lord Buddha's family/cast (Shrathriya/Shakya) was at the top of the casts at the time and they were very proud of it.Once a kind requested a princess for a marriage from Shrathriya/Shakya cast.But because of their ego they tricked the king by sending a pretty slave girl as a princess.Time went by and she had a son,he visited the Shrathriya/Shakya relatives one day and went back.But one of his men forgot his weapon and came to get it back.That's when he heard what a slave was saying while she was eagerly washing the room that prince stayed in, She was saying look how high a slave's boy has come. The guard went back and said the whole story and the truth was revealed.He took his army and came to kill all the Shrathriyas/Shakyas.Lord Buddha saw this and stopped him not once but twice.In the third time Lord Buddha looked back in time and understood that these people are about to be slaughtered as an effect of a old Karma.This time lord Buddha did nothing.The prince went and killed all of the Shrathriya/Shakya cast brutally.That is why there is no more left today from Lord Buddha's family."
Lord Buddha said that we must come above the lust to be alive,to be born,to not to exist.Lord Buddha said that we must understand the impermanence.But we as normal people still love to live.
If you look into Buddhism you will see how many villages,casts,races have faced death/genocide. Whether we like it or not the only option is to stand like men an take it because if we raise an arm we commit bad Karma.
What happened in Myanmar can't be justified. That is not the advice of Lord Buddha.We are not permitted to kill.
You can't be a Buddhist and a warrior at the same time,it is simple as that.
This might be a hard pill to digest but here is a good example why this concept is right...
Khantivādī Jātaka: J 313 (A Bodhisattva story of our Buddha)
In the Jātaka Tale, Patience Teacher Birth Story (Khantivādī Jātaka: J 313), a jealous king repeatedly asked an ascetic what the ascetic taught, to which the ascetic replied, "Patience," which the ascetic further defined as "not to get angry when injured, criticized or struck." To test the ascetic's patience, the king had the ascetic struck two thousand times with a whip of thorns, had the ascetic's hands and feet axed off, cut off the ascetic's nose and ears, and then kicked the ascetic in the heart. After the king left, the ascetic wished the king a long life and said, "Those like myself do not feel wrath." The ascetic died later that day.
Kshanti (Sanskrit kṣānti) or khanti (Pāli) is patience, forbearance and forgiveness.1 It is one of the pāramitās in both Theravāda and Mahāyāna Buddhism.
It is comforting to have the licence to kill but as Bodhisattva's had done for eons there is only patience and Kshanti for a Buddhist. Go to India and ask what happened to the Buddhists, all of them were impaled on Trishulas by Hindu people. This is not the only time a Genocide happened. No matter who is the victim it is only wrong. Imagine why a teaching like Buddhism vanishes every time it appears in this world, every time it has been a genocide. Your mind will not support the idea first but if you read enough sources the massage is clear. Lord Buddha said one must not harm or kill another even if it cost him his own life .You can either be a Buddhist and make your mind to die the glorious death in Kshanti or you could pick a weapon and go to war. This is where we differ from Christians,Hindus and Islamic, With all due respect to them we do not have a holy war. A good Buddhist is ready to happily accept the other end of the gun.
The offensive of a Buddhist King
But if you are a rebel i recommend you learn the story of** King Dutugamunu . This King protected the lives and the Theravada teaching of srilanka against the Hindu invader's Genocide. As to the prophecy this king will be one of the Great followers of Maithri Buddha in the future.