The US Department of Agriculture (USDA) said it removed the fictional country of Wakanda from an online list of nations that have free trade agreements with the United States on Thursday.
The Kingdom of Wakanda is the home of Black Panther, the Marvel superhero, and is portrayed in comic books and the 2018 blockbuster movie as an isolated African nation with the most powerful technology on the planet.
"While we removed the Kingdom of Wakanda from our list of US free trade partners, our relationship will always be strong #WakandaForever," the USDA tweeted from its official account.
The agency did not immediately respond to questions.
A spokesman told The Washington Post that inclusion of the mythical African nation from the universe of Marvel superheroes was a mistake made as part of a test officials were running.
Francis Tseng, a New York-based software engineer who was looking for data on US agricultural tariffs for a fellowship he is pursuing, first noticed the reference to Wakanda on the US tariff list and called it out on Twitter.
"I was very confused at first and thought I misremembered the country from the movie and got it confused with something else," Tseng told Reuters.
Before it was removed, Tseng managed to download an Excel sheet listing "Harmonized Schedule" tariff codes for various categories of goods traded between Wakanda and the United States including live animals, dairy goods, tobacco and alcohol.
After the list was corrected, Tseng tweeted: "Well, the USDA took Wakanda off the list. Guess we're in a trade war with them too."
There was no USDA entry for vibranium, the fictional metal from space that is the source of Wakanda's power.
Marvel is owned by Walt Disney Co.