[Malcolm Reynolds]

Maybe getting to the port itself, but not beyond. I'm guessing we also have ways to monitor nuclear material at sea.

https://www.dhs.gov/blog/2017/04/06/new-radiation-detection-system-operational-major-us-port

[Spktyr]

It’s a nuke. You don’t even have to get the ship tied up in the dock. Set it off in the middle of the harbor for maximum devastation.