Travelling to the United States has always been something Iranians like Agency for Science, Technology and Research scientist Omid Geramifard have had trouble with.
And the recent temporary ban on people from seven Muslim-majority countries, such as Iran, entering the US does not help - it has prevented his parents from visiting his brother who is based there.
"I don't feel good about it at all. It does affect me from travelling for business or visiting family members there," said Mr Omid, 31, who has been based in Singapore since January 2009.
His parents had wanted to fly from the family's hometown in Shiraz, Iran, to Dallas in the US in mid-March to see their second grandchild who is due in April. They have American visas valid for travel till then.
Mr Omid's parents - Ms Roghayeh Saboorishirazifard, 60, and Mr Mohammadhadi Geramifard, 69, both retired teachers - were in Singapore to help him and his Iranian-Canadian wife following the birth of their daughter in August last year.
Mr Omid, who has three siblings, said his parents have chosen not to risk travelling to the US now because they heard that valid visa holders had been denied entry by some airlines.
He said: "My parents don't want to be subjected to interrogation in a foreign land. It's supposed to be a happy moment seeing family members and their second grandchild... Now, they're disappointed."
Mr Omid said difficulties travelling to the US are not new for Iranians and that the ban was "not something that suddenly surfaced". He said Iranians are usually selected for security checks at border checkpoints.
"Now, they're just calling it out explicitly, and being more open about it and saying that people from these countries have to be treated differently," he said.
His visa application to travel from Iran to the US to further his studies at the University of Georgia was rejected in 2008, even though the school had accepted him. Mr Omid then decided to head to Singapore instead where he was awarded the Singapore International Graduate Award in 2009 for PhD studies in machine learning at the National University of Singapore. "To be honest, I love Singapore and the way I've been treated here," he said. "I'm really grateful to be in Singapore, and for making the decision to study and work here."