The Iranian-born BBC journalist was reportedly held for two hours
British citizen Ali Hamedani, who was born in Iran, said he was forced to hand over his phone and its password so it could be scoured for his political views.
The BBC World Service reporter's social media accounts were probed despite him having travelled to Chicago's O'Hare airport from London Heathrow while holding a British passport.
The Foreign Office has since said it was told by the US that extra checks would be performed on UK citizens only if they were dual nationals travelling from one of seven counties, which are predominantly Muslim.
Mr Hamedani told Radio 5 Live's Stephen Nolan: "So they took away my phone and they started searching and I saw the guy searching my Twitter account.
"So they were looking to find about any kind of political views, whether I'm supporting anybody – any kind of extremist idea or not.
"They also asked me questions about whether I have been trained by the military, if I had been trained in military bases in Iran or when was the last time I was back home in Iran.
Mr Hamedani told how US border controll officers took his phone and searched his Twitter account
They were looking to find about any kind of political views
"It wasn't pleasant at all. To be honest with you, I was arrested back home in Iran in 2009 because I was working for the BBC and I felt the same this time."
Mr Hamedani, who landed at around 4.40pm UK time on Sunday and has rescinded his Iranian passport, said he was met by protesters after making it through security.
He said: "The very touching moment was when I came out of the whole thing, when I came out into the arrival hall, I have met more than 50 people, most of them American … and they hugged me and they welcomed me and they were trying to say 'this is not the real America, we are the real American people'."
Mr Hamedani was greeted by a crowd of protesters who welcomed him to the US
His ordeal came ahead of the Foreign Office saying Foreign Secretary Boris Johnson had been told by the US president's team that Britons with dual nationalities would not be barred from entry.
Mr Johnson was also told that heightened scrutiny for dual citizens would only apply to individuals travelling directly to the US from Iraq, Iran, Libya, Somalia, Sudan, Syria and Yemen.