Offer your thoughts or opinion on the input financial query or topic using your financial background.

US sanctions against foreign citizens 
US Sanctions are usually very nuanced and you should look them up yourself.  It may be widely reported that "US sanctions X-country" and it may be widely understood that it means all funds from anybody in that country are blocked, that USUALLY isn't the case (or "many times" isn't the case, I'm not going to bother quantifying that) Many times it is a comprehensive list of certain individuals and businesses that are blocked. The US Treasury publishes a list of these organizations. This misinterpretation can trickle down to companies. You would think big financial companies understand regulations, but they typically just react to how things are reported and have no uniform understanding of the financial regulations they are subject to. Private companies create unique and arbitrary company policies in reaction to the spirit of a regulation. So could it be that all Iranians cannot interact with the US financial system? Sure, thats possible. Could it be a lot more nuanced? Sure. Does it matter if the broker will actually investigate your SSN with USCIS? Maybe, maybe not. Does it matter if you disclose you are a dual citizen if they claim they can just check your SSN?  The financial institution is the one liable for misinterpreting sanctions. Let the consequences guide your actions.