According to a spokesperson with Customs and Border Protection, the team arrived in Chicago from Dubai.
Two people with the team underwent what's called "additional inspection."
ABC News reports one of them was the Iraq's World Cup striker Aymen Hussein, who was allowed in after being questioned for nearly seven hours.
But the CBP spokesperson says a photographer was determined to be "inadmissible" and was denied entry "due to classified information in accordance with U.S. law."
Full statement from CBP:
"On June 5, the Iraqi national team arrived at Chicago O'Hare International Airport from Dubai International Airport. During processing, two travelers underwent additional inspection, a routine part of CBP's inspection process when officers need to verify information or determine admissibility.
Following inspection, one traveler was admitted to the United States. The second traveler, a photographer and NOT a player on the team, was determined to be inadmissible and was denied entry due to classified information in accordance with U.S. law.
All travelers seeking entry into the United States, including athletes, coaches, and staff, are subject to CBP inspection and vetting. Admissibility determinations are made on a case-by-case basis using law enforcement, national security, and immigration information available at the time of inspection. CBP officers have the authority to question travelers, conduct inspections, and determine admissibility consistent with U.S. law."