I don't want to get into the 'who's a hostage-taker' discussion here but what is the estate tax? It's a double tax on death. Economists will tell you that it's really not a tax that soaks the rich but it's a tax on capital that deprives business investment and therefore job creation.
Certainly protecting oppressed people stopping ethnic conflict and promoting responsible governance are worthy goals. But none is as important for American security and prosperity as keeping the peace in the Middle East Europe and East Asia.