The opening ceremony of theon Friday was marked by audible boos from the crowd as delegations from the US and Israel entered the San Siro stadium.
US Vice President JD Vance and Secretary of State Marco Rubio led the American delegation.
As Vance appeared on the stadium's big screen, waving the US flag, the crowd responded with jeers, according to live coverage of the event.
"There is the Vice President JD Vance and his wife Usha. Oops -- those are a lot of boos for him," an announcer was heard saying during the broadcast.
The reaction followed days of tension surrounding the participation of US Immigration and Customs Enforcement (ICE) agents in Olympic security.
The Department of Homeland Security confirmed the presence of Homeland Security Investigations personnel in Milan, prompting widespread protests and opposition from Italian lawmakers and citizens.
"They're not welcome in Milan," said Milan Mayor Giuseppe Sala in a radio interview, calling ICE a "militia that kills."
Thousands gathered in Piazza 25 Aprile last weekend to demonstrate against the agents' presence and raise concerns about civil rights violations.
International Olympic Committee President Kirsty Coventry responded to concerns ahead of the ceremony, saying: "I hope that the opening ceremony is seen by everyone as an opportunity to be respectful of each other."
The Israeli delegation, which included nine Olympians and one Paralympian, also faced a "smattering of boos" as they entered the stadium, though the crowd noise was largely drowned out by music.
Additional protests were reported in Cortina d'Ampezzo and Predazzo, where simultaneous parades were held.
Security remains a top concern for several delegations, with increased attention to political sensitivities throughout the Games.
More than 800 athletes have been killed in Gaza since the start of Israel's offensive on Oct. 7, 2023, as the sports community continues to suffer under bombardment, famine, and the collapse of infrastructure, according to Palestinian officials.
