Okay so according to another outlet, there was an order signed Monday but I haven’t found it yet.
The ban on Americans doing business with Venezuelas government takes effect immediately.
All property and interests in property of the Government of Venezuela that are in the United States ... are blocked and may not be transferred, paid, exported, withdrawn, or otherwise dealt in, the executive order says.
https://www.theguardian.com/us-news/2019/aug/06/trump-freezes-all-venezuelan-government-assets-in-us
The order, signed by President Trump on Monday, cited Maduros continued usurpation of power and human rights abuses by those loyal to him.
So is Citgo effectively shut down?