When I've talked to my T about world events (pandemic, Ukraine, etc.) the conversation generally centers on accepting that some things are completely out of my control, and figuring out what I want to do in my own life, in the realm of things that I do control. It's important to know what's going on, and respond in the ways that are possible, but beyond that, I'm an average person without enormous power and my sitting around worrying about nuclear war won't change a thing.

On reassurance in general, my T has said he doesn't do reassurance because it doesn't work. If he says "everything is okay" it might feel good for a second but that won't last because it doesn't address the source of anxiety. Better to figure out what the anxiety is really about and where it comes from, and then maybe you can get a better handle on how to deal with it.