Nobody is 100% sure. The thought is they are 10 years away, but they did fire on Diego Garcia this year. The missiles went about 2500 miles but were intercepted or failed. They could likely hit many of our allies in Europe (assuming we don't intercept them), and certainly our middle-eastern allies. They need to almost double that range to hit the USA. Alaska is around 4100 miles and is the closest point for them.

We also have a bunch of bases that are within their known range. The other issue is one of their allies could give them a missile that can reach us. Of course they could easily just move missiles closer via storage containers. Not much we can do about that one.