Hi Masha,
There are so many factors that impact your question, that no answer you get here is going to be complete.
In addition to all of the factors of markets, research, planning, etc for the 'start-up' part, you will have to decide which country will host the 'domestic' and which the 'foreign' parts of the company. Just like the US has regulations regarding business operations, and taxation, and employee withholding, I'm certain the Ukraine will also have its share.
These factors can be very different in how they are administered, and even how the rates of fees/taxation between a 'foreign' and 'domestic' operations are applied. You should have a very good attorney in both countries to advise you BEFORE making any investments. It just may be that you will want to look at starting two separate companies.
Then there are the mechanical parts. You will have responsibilities under Customs, Immigrations, and a variety of US laws on import and export restrictions. The Ukraine may also have such issues. Research!
Costs and means of shipping, etc will also be considerations.
If you are pursuing this alone, at this time, I'd suggest the trade secretary at the Ukarainian embassy or nearest consulate.
Good Luck!
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