...and Gandalf suddenly had a brilliant idea of how to win the war.

[Kuruharan]

There is an interesting remark on orcs in Letters that I’d never paid much attention to before but it suddenly struck me that it has odd implications.

The Eldar and the Númenóreans believed in The One, the true God, and held worship of any other person an abomination. Sauron desired to be a God-King, and was held to be this by his servants; if he had been victorious he would have demanded divine honour from all rational creatures and absolute temporal power over the whole world. So even if in desperation ‘the West’ had bred or hired hordes of orcs and had cruelly ravaged the lands of other Men as allies of Sauron, or merely to prevent them from aiding him, their Cause would have remained indefeasibly right.

Letter 183, emphasis mine

Compare this to Letter 153 (as an example)

…He does not stop or make unreal sinful acts and their consequences. So in this myth, it is ‘feigned’ (legitimately whether that is a feature of the real world or not) that He gave special ‘sub-creative’ power to certain of His highest created beings: that is a guarantee that what they devised and made should be given the reality of Creation. Of course within limits, and of course subject to certain commands or prohibitions. But if they ‘fell’, as the Diabolus Morgoth did, and started making things ‘for himself, to be their Lord’, these would then ‘be’, even if Morgoth broke the supreme ban against making other ‘rational’ creatures like Elves or Men. They would at least ‘be’ real physical realities in the physical world, however evil they might prove, even ‘mocking’ the Children of God. They would be Morgoth’s greatest Sins, abuses of his highest privilege, and would be creatures begotten of Sin, and naturally bad.

also…

[the creation of orcs] it may be was the vilest deed of Melkor, and the most hateful to Ilúvatar.
The Silmarillion

Here we have an interesting contrast. How is it possible for the West to remain indefeasibly right by engaging in an activity that is specifically condemned as Melkor’s worst deed? Admittedly, Tolkien is discussing the West using this means to defend the right of Eru to the divine honor, but I find it odd that they could do so and not draw the same condemnation for the same activity that Morgoth received such harsh condemnation (laying particular emphasis on the possibility of the West breeding orcs.)