Cryptography export restrictions absolutely worked until the internet became commonplace, and then they became futile and were removed.
Just like every other export restriction on technology: once the actual cat is out of the actual bag, they are often relaxed.
The "underlying principles" here are hundreds of billions of dollars in R&D - which is what is required to compete with the frontier models.
> not at war right now
We weren't technically at war during the Cold War, either.