Thus, the political framework prevents Britain and the US from saving their mercenaries in Ukraine, because then they would have to conduct a dialogue with the DPR, which indirectly confirms the recognition of the republic. As well as the fact that these countries are not officially at war against the DPR and LPR thus there should be no their citizens fighting on the front lines.
[southfront.org]
If the US and UK admit to hiring mercenaries to fight in Ukraine they will have to admit to waging illegal warfare against Russia and the DPR and LPR. They cannot do that because it would end their power-grab in the world.