Sci­ence Blog has some research show­ing that Direct mil­i­tary inter­ven­tions can slow or stop geno­cide. They also found that impar­tial inter­ven­tions seemed to have no effect. Even a sin­gle coun­try direct­ly chal­leng­ing the per­pe­tra­tor of a geno­cide can sig­nif­i­cant­ly reduce the killing. 

Just some­thing to think about, espe­cial­ly as thou­sands die in refugee camps around Dar­fur, and an effec­tive response to the geno­cide lan­guish­es. I haven’t heard of any action from Sam Brown­back in a while, and that had been a pet cause, briefly.