Can you cash a US treasury check in the Netherlands?

Obviously, you need access to the physical check, either you or someone you trust must have it in his hands.

Most major banks now have cellphone deposit apps, that allows you to submit it from wherever you are; if you have trusted person, he/she can deposit in your absence with the app and your bank login (take trusted serious here!).

What I did in a similar situation, I had my 'trusted person' fake my signature, and send my pictures of front and back of the check in an email (with some space around them). Then I (being in Europe) used the app, logged in, and photographed those pictures (you'd need a second device that displays the email attachment!) as if they were a check.

Note that faking the signature will pass, as long as you don't complain to the bank; they do not compare the signatures unless there is an inquiry.

Note: That might still be technically considered 'fraud' or 'check fraud' - I am not a lawyer. I am saying it works, and nobody is cheated, so I did it. You are on your own.

If this is an alternative, you can deposit the paper check (if you have it) into a bank in Europe (your account or a friends, if you are physically there with him). This will take time, however, several days to clear, expect 7 - 10 days.