Torrents are peer to peer. Bit torrent is a type of application. Bittorrent are not inclusive to torrents anymore.
Since everything is public, you can load several torrents, and watch for the handshake to occur and record the time/date and ip address.
Do it on a large enough scale and there you go.
There are many ways to secure against this, usually USA IP holders use USA cloud services or USA IP addresses. Some are public, but even if not, you can block the entire USA , so geoblocking by a simple tool such as: https://www.countryipblocks.net/acl.php
And you're pretty much in the clear. Not perfect, but pretty much.