The British Chief had batter have a conference with the defense ministers of the other NATO members and make sure they are on board.
Britain only has two (2) deployable divisions.
I think the British COS is telling his bosses what may happen as well as telling his troops. To me it is a bit of realism that needs to be thought about, especially since I don’t think anyone in the West can accurately predict what Putin may do. And I don’t think either the SecDef or Army CoS Milliey have done any realistic thought on this.
I’m not for any US participation other than what we are currently doing in providing weapons and supplies to the Ukrainians for their self defense.