How to make war and peace

It's time for our once per quarter sermon about Current Events, where we scour that week's headlines searching for what everyone's talking about.  This week, as it has been for over a month, the top headline is the Russian invasion of Ukraine.  The purpose of the Current Events sermon series is to think Christianly about what is happening in our world, and thus in this sermon Joel Kime talks about Just War Theory and Pacifism.  What does the Bible say?  Can Christians support war?  Can they support and join the military?  Why do some Christians say "Yes" and other Christians say "No"?