Why TF not, Einstein?
This war is not a Russia vs Ukraine war, it is a USA vs Russia war. It's not even debatable. The war would never have occurred, much less gone on for years, without the $250,000,000,000+ the USA processed through the Ukraine laundromat.
Above your pay grade, and mine too.
Let me speculate, we don't have an unlimited number of THAAD systems.
We are provoking a trans arctic ballistic missile attack.
If you were in charge would you deploy THAADs to defend Kiev or Washington DC (where you live)?