I believe if the government could force Anthropic to block access completely they would have done so. An ITAR classification is the most they can legally do at this moment.
Effectively though, it has blocked it for everyone. It's not an available model right now, Anthropic doesn't have a way to verify US citizenship at this moment, so its offline for all general customers at this point.
Which sucks, I was planning to start using it on Monday at work. Lesson learned, when this stuff comes out use it immediately before it gets blocked.
I don't have a good answer on this. I don't like what just happened, but I don't see a good path going forward. These tools are so powerful, they make any body with a laptop and internet access capable of extremely widespread damage. On the other hand, they can't be stopped, it's not like the US is the only country working on this, and the speed at which these models are growing makes it likely that an LLM with Mythos capabilities is downloadable for anybody for free within the next 12 months
This is really spiraling quickly