It’s not the submarine software, but the manufacturer’s intranet. Likely based on Sharepoint:
https://www.reply.com/wm-reply/en/> WM Reply are … specialising in Microsoft 365
And it’s a £500k contract, which doesn’t get you very far in corporate intranet land.
But of course it presents a security risk, since the intranet usually is the gateway to people or project information.
And I am truly puzzled by how they knew it wasn’t appropriate to hire subcontractors in Belarus and Russia, but talked themselves into making it ok. Even suggesting to put names of dead people in the reports.