By Ahmed Elshamy & Owen Pinnell
BBC News Arabic
By Marc Weller
Professor of International Law
By Frank Gardner
BBC security correspondent
Iranian businesses explain why they are becoming increasingly isolated and frustrated.
US President Donald Trump has signalled tough new sanctions on Iran could be on the way.
The move is in response to what US officials say was likely Iranian involvement in an attack on Saudi oil facilities.
Mr Trump made the announcement on Twitter late on Wednesday, and said there would be more details within 48 hours.
The current US sanctions on Iran are already wide-ranging, aimed at reducing country's oil exports and crippling its economy.
By Anahita Shams & Reality Check team
Feeling the squeeze: Iran sanctions explained in five objects
The BBC has been given rare access inside the country as tensions increase with the United States and its allies.