The visa rules date from the Obama administration, and are unconnected to President Donald Trump’s controversial travel ban, which targets Iran and five other Muslim-majority countries.

The system prohibits Estas for any citizen of 38 countries who visited Iran, Iraq, Libya, Somalia, Sudan, Syria or Yemen after 1 March 2011.

They must instead apply for a visa, which involves a face-to-face interview at a US embassy or consulate.

…The former Nato chief blamed “an algorithm” for the denied application, and said he needed entry to the US because he teaches at various universities.

British-Iranian BBC journalist Rana Rahimpour was denied entry to the US in January 2016, despite her dual nationality

Former Nato chief Javier Solana denied US visa waiver – BBC News

hmmmm