Given indifference curves for Sam and Tom for products X1 and X2, I calculated that it is possible to trade to make both better off. I am OK with this part. My question is about the impact of geographic location, which assume Sam and Tom are far away from each other.

However, if Sam is in Europe but Tom is in US, will this new fact change my answer above?

I think X1 in Europe is not the same as X1 in US, so Sam and Tom can no longer trade to make both of them better off. Is my answer correct?