A full panel of 13 judges from the 4th US Circuit Court of Appeals heard arguments on the third version of Trump's travel ban.
It was the second federal appeals court to hear a challenge to the ban this week, following a hearing Wednesday before the San Francisco-based 9th Circuit.
The hearing came four days after the US Supreme Court said it would allow the travel restrictions to go into full effect, at least until the two appeals courts ruled on separate lawsuits challenging the ban.
North Korea and Venezuela are also included, but to a much narrower extent.
Deputy Assistant Attorney General Hashim Mooppan told the judges that the latest travel restrictions were the product of a global, multiagency review that found the countries do not share enough security-related information with the United States. He insisted the latest travel ban is not anti-Muslim, but is necessary for national security.