The US / UK could have bombed / sabotaged the railroad tracks, all support systems leading to the camps, assassinated the camp commanders. There was much that could have been done. But FDR and his crew did not give a sh*t about the Jews. One of, if not the worst chapter of American history.
Today we have another Holocaust - Sudan. What is the US doing about this? What is the US doing to prevent Africa from falling into the hands of Islamic Jihad? Read what's going on here: South Sudan News
We didn’t have the bombing assets to spread all over and mounting missions deep into enemy lines to “assassinate[d] [the] camp leaders”? Deep penetration sabotage missions?
When people are fighting for survival, and fighting globally against the world’s most powerful militaries, they can’t do everything, and the things that you describe are more difficult than in the movies, how many troops has Israel sent to Sudan?