I'm in US my rings are in UK can I do anything?

I was engaged to someone in the UK (Clydebank Scotland) and had purchased myself the wedding bands we found so we could have the one's we wanted for sure, they were mailed to him there.

He broke up with me, I asked that they be sent and there was an agreement that they would be send, now he has said he will not he wants to 'throw them in a river'

I really want those rings that I paid for... is there anything I can do?

Thank you

Amanda