The Turkish government published a presidential order. That was on 31 December 2020 in the Turkish Official Gazette. It says that unshelled walnuts import tariffs would increase to 15%. That's for all countries of origin, except those with a free trade agreement with Turkey.
There's also an additional ten percent duty, on top of the 15%, on nuts from the United States. This is a countermeasure to the increase in US tariffs on Turkish steel. So, US walnut producers can count on a 25% customs tariff, as it was before August 2020.
The US Department of Agriculture has done a preliminary analysis. It shows that this tax amendment will have a minimal effect. That's on the cost of US-sourced walnuts for Turkish buyers. It won't affect the demand for US walnuts in Turkey either.