Being a pacifist is one of those things that sounds like a virtue, but really isn't. Imagine a bully beating up on an old lady while you stood and watched and did nothing, because you philosophically don't believe in hurting others. Does that make you virteous? I don't think so. Then imagine standing around while the bully took out all the other people watching, one by one, except you. What do you think would happen next? Obviously he will then go after you. Does that seem smart?
War is a necessary evil. The best way to assure peace is to have a strong military. My husband is a retired Army warrant officer, he is the most peaceable person I know, but he knows that in order for religions like the Jehovah's Witnesses to exist, someone has to do the dirty work that they won't do. If the US did not have a strong military, how long do you thing it would be before radical Muslims took over? How many Jehovah's Witnesses would there be then?
The JWs are so proud of the fact that they were persecuted in Natzi Germany, being willing to go to the concentration camps before they violated their pacifist stance, but if others had not been willing to go to war the Natzis would never have been stopped and we would all be speaking German now. And the Jehovah's Witnesses basically volunteered for the camps, they could have avoided them by pretending to support Hitler. There really is no virtue in being stupid. It's also hypocritical, as the Watchtower hides and lies about their past, and practices "spiritual warfare"; in other words, lying. So what is better, refusing to tell one lie, going to the camps and providing free labor for an evil regime, or doing what you need to do to avoid that and then working to bring down that regime?
Also, the JWs justify their pacifist stance by insisting the world is ending soon, so it doesn't matter which governmental is in power, but since they are mistaken about being in the last days, it makes that argument meaningless.