Would this mean Any systems built with Claude in defense environments may need to be rebuilt or removed?

From what I understand it cannot be used to perform work on contracts where the DoW is on the other side. [1]

In practice I would suspect companies with such contracts would play it safe by outright banning the use of Anthtropic products, even if they could technically be used for work on contracts with other parties.

[1] https://www.anthropic.com/news/statement-comments-secretary-...