“Mr. Obama’s actions would not bar the targeted Russian banks or energy companies from doing business with Americans or seize their property. Rosneft, for instance, has major joint ventures with ExxonMobil that will still be permitted. But administration officials pointedly noted that such moves were still possible if Russia did not back down.
Craig Pirrong, a professor of finance at the University of Houston, said the current moves might not have that much impact because the affected companies could get American dollars elsewhere. “This will constrain to some degree the size of the capital pool that the sanctioned firms can access, but not nearly as much as could be,” he said.”