This is not how ship registration works. A useful model is to think of a ship's flag like a tld, just because a site is .cn doesn't mean the company is based out of China. Ships usually fly one flag or another based on tax and legislative reasons, and it's often unrelated to the country of origin.

The ship suspected of breaking the cables has been apprehended and it turns out it was currently sailing from Russia with a Russian captain [0].

[0] https://x.com/visegrad24/status/1859132263746744367