Treat "based in Europe" as a claim you verify. Check identity through a reliable procedure, compare details across CV, contract, payroll account and delivery address, and contact former employers using contact details you found yourself.
The US government also recommends in-person meetings where possible and shipping company equipment only to an address that matches the ID documents.
In our Delivery Sprint, this fits into steps we already run. The intake agrees on what the role needs. Sourcing is done by senior recruiters who talk to every candidate. Interviews are live and repeated, with a spontaneous technical conversation instead of a rehearsed one. A fake profile has a hard time surviving three live conversations with people who know the market.
After the hire, keep access small at the start. Give new remote hires limited credentials and no production, source-code or secrets access until screening is complete. Then watch for logins from inconsistent locations, odd working hours, remote desktop tools and the same IP address across supposedly unrelated employees.
Finally, make sure HR, legal, security and sanctions compliance know who does what if something looks wrong. That route should exist before the first incident.