I was born in Belarus and now live in the US, so I have two addresses.
I was asked what is my foreign address and I gave them the US one, however they say the foreign should be my Belarusian one.
My question is what is the foreign address in this case?
P.S. I am not a US citizen.
It all depends on the nationality and location of the organisation asking the question. If the questioner was American, then your "foreign" address would be your Belarusian one; if the questioner was Belarusian, then your "foreign" address would be your US one. The point is that the nationality of your address is relative to the questioner, not to you.
I'm not a teacher of English, but I have spoken it for (almost) all of my life....