Artan, who was due to break new ground as the first Somali referee to take part in football's grandest stage, was denied entry after arriving to Miami International Airport from Istanbul on Saturday.
"During processing, the traveller underwent additional inspection, a routine part of CBP's inspection process when officers need to verify information or determine admissibility," US Customs and Border Protection said in its statement.
"Following inspection, the traveller, a referee for the FIFA World Cup, was determined to be inadmissible due to vetting concerns and was denied entry."
FIFA confirmed later on Monday that Artan wouldn't be able to train and officiate at the World Cup.
"FIFA is not involved in host country immigration processes, including visa adjudications, and has been informed by authorities that Mr. Artan's status will not be changed at present," FIFA said in a statement.
"In line with previous FIFA events, a host government ultimately determines who receives a visa and who is admitted into their country."
Artan, the 2025 Confederation of African Football (CAF) men's referee of the year, was due to be one of 52 main referees at the tournament
He is the latest official refused entrance to the United States.
Former Socceroos coach Graham Arnold's Iraq also ran into problems upon arrival.
Striker Aymen Hussein was held and questioned for nearly seven hours at Chicago's O'Hare airport, though he was able to enter, while team photographer Talal Salah was turned back.
Iraq's football association posted a message on social media referencing the absence of Salah and injured player Ahmed Yahya.
"Even if you're absent from the scene… your impact remains present," the post on X read.
"A player sidelined by injury, and a photographer kept away by circumstances… yet their names will always remain part of the World Cup journey.
"Absence is only temporary… but the impact lives on forever."
Swiss striker Breel Embolo was initially unable to travel with his teammates last week after he was denied an ESTA (electronic system of travel authorisation), due to extra checks related to previous court cases.
The striker submitted a request for an urgent visa and was ultimately cleared to travel, though he didn't feature in Saturday's 1-1 draw with Australia.
With AP
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