Knee jerk response? Demand King Charles no longer be our king.
Honest response? What's the war over? If the UK is mass killing people (they have a history of that), then the US. The US is mass killing people (they have a history of that), then thr UK.
Maybe we should grow beyond the last century's call for war better get to killing response. Maybe Canada should feel bad about its role in the Boer war, for example, or question what we should have done differently in the Korean War, and perhaps nuance needs to be done.
Maybe the two old heads of state on each side should have to fight to the death or negotiate rather than millions of the world's poor sent through generational hell so one side can have more money.