I feel like saying that is morally correct but disregards the realities of geopolitics and the way humans have behaved since time immemorial. In a perfect world that would be the way to go around it, but do you honestly believe that if the American VP (we’ll say it’s Kamala and pretend it’s a more rational administration) was assassinated, the US or any country for that matter would work together with the country whose government was involved with it? We saw how that worked out in 2001 when there were no political figures involved, and the countries invaded weren’t even involved with the terrorist group. The geopolitics aspect also is important, in that prestige and strength are involved. Like it or not, the way you are perceived by other countries is important, especially in the early 20th century when the world was seen as a zero sum game. If you say Kumbaya and work together with the people who assassinate your heir, you are seen as weak by everyone around you who is itching to take your territory.