The United States has exempted territories in Syria run by the Kurdish militia, the People’s Protection Units (YPG) from wide-ranging sanctions.
This is a decision which neighbouring Turkey has condemned as an attempt to legitimise the group.
The move by the US Treasury Department on Sunday lifted numerous prohibitions from areas primarily under the control of the YPG.
The Middle East Monitor added that it would enable companies to engage in the fields of agriculture, telecommunications, power grid infrastructure, construction, manufacturing, trade, finance, and clean energy.
The ruling also allows some foreign investment into the areas which span from the Aleppo governorate in the northwest to the Hassakeh governorate in the northeast.
Oil from those exempted areas can also now be purchased, on the condition that it does not benefit the Syrian regime of Bashar al-Assad.
Business with the Assad regime is still generally covered by the sanctions and is officially prohibited, as is the importing of Syrian oil to the US.
Turkey has condemned the move with President Recep Tayyip Erdogan telling reporters in Istanbul that the YPG is a terrorist organisation.
Over the past five years, the US has supported and armed the YPG and its umbrella Kurdish partner group the Syrian Democratic Forces (SDF). That support has over the years angered Turkey, which has accused the US and European nations of essentially supporting terrorism and threatening Turkish national security.