I understand that nationalities eligible for VWP cannot enter the US without seeking clearance and obtaining a sticker visa from US embassies if they have travelled to Iran, Iraq, Syria & Sudan since March 2011.
But what about citizens from countries that require a US visa to travel to the US, what if they have a valid US B1/B2 visa AND visit Iran/Iraq AND then visit the US soon after? Is there anything to suggest that the visit to the restricted countries would invalidate their existing US B1/B2 visa?
Let me add an example: suppose a citizen of Pakistan or Turkey or Lebanon, who holds a US B1/B2 visa which has been used once, visits Iran and Iraq for tourism/pilgrimage purposes and after a few months arrives at the US port of entry and seeks admission. Is there anything wrong with this scenario?