New York Mayor Zohran Mamdani.New York Mayor Zohran Mamdani arrived at the 9/11 Memorial & Museum at Ground Zero on Friday to attend the 25th anniversary commemoration of the September 11, 2001, terror attacks, despite calls from some victims' families and former New York mayor Rudy Giuliani to stay away from the ceremony.Mamdani was later seen shaking hands with Giuliani at the remembrance ceremony, with the two appearing cordial before briefly parting ways.The interaction came days after Giuliani had publicly said Mamdani's presence at the ceremony would "offend him" and urged the city's first Muslim mayor not to attend.The annual remembrance ceremony, hosted by the 9/11 Memorial & Museum, is attended by victims' families, first responders, dignitaries and other invited guests. Vice President JD Vance and former presidents Joe Biden, Barack Obama, Bill Clinton and George W. Bush were also expected to attend.Calls for Mamdani to stay awayMamdani's attendance had faced opposition from some relatives of 9/11 victims. A petition launched by victims' family members urging him not to attend had gathered roughly 110,000 signatures.The campaign against his attendance largely focused on Mamdani's appointment of Ramzi Kassem as New York City's chief legal counsel. Kassem had previously represented Ahmed al-Darbi, an Al Qaeda operative who pleaded guilty to war-crimes charges.Former New York governor George Pataki had also echoed calls for Mamdani to stay away from the ceremony, while Giuliani had criticised the mayor's decision to attend.The controversy intensified after Mamdani handed a ceremonial pen used to sign 9/11-related executive orders to NYPD Commissioner Jessica Tisch and asked her to pass it to Kassem. Critics on social media characterised the move as disrespectful to relatives of those killed in the attacks.Mamdani defends attendanceMamdani has defended his decision to attend the ceremony, saying the focus should remain on the families who lost loved ones, first responders and New Yorkers who came together after the attacks."I'm proud to be the mayor of this city. I love this city. I love this country," Mamdani said, adding that he wanted the week to focus on the families whose loved ones were killed 25 years ago, as well as first responders who gave everything to the city.The mayor had also faced criticism over his past comments and associations related to the Israel-Palestine conflict and 9/11.He has since called Twitch streamer Hasan Piker's comments that America "deserved 9/11" "objectionable and reprehensible" and said he would discourage people from using the phrase "globalize the intifada."