in my basket, for products from US there's a note under the items. There's also a warning at the top of the page saying there's no returns or cancelling for them
see attached picture.
If you can't figure it out ...
Open each item you added to list in a new tab (click on scroll wheel or right click , T for "open in new tab") then look at the page... at availability it says "US stock" if it's sent from US.