The United States warned businesses against participating in an annual trade fair this week in the Syrian capital, Damascus.
The US Embassy in Syria, which closed the mission early on in the country's eight-year civil war, posted a statement on Twitter ahead of the Damascus International Fair, which is expected to open on Wednesday.
The statement said anyone doing business with Bashar Assad's regime will expose themselves to the possibility of US sanctions.
It added that it is "unacceptable and inappropriate" for businesses and individuals to participate, particularly at a time when the regime, aided by allies Russia and Iran "are attacking innocent civilians."
The Damascus International Fairgrounds near the Damascus airport are hosting the fair.
It used to be a high-profile event before the war started in 2011, attracting major investors.
