Every day？ for the past week, Kim Kwon-seop, 72, has joined thousands of others gathered near the home of South Korea’s impeached president, Yoon Suk Yeol？. They were determined to shield Mr. Yoon from prosecutors who wanted to detain him on insurrection charges stemming from his short-lived declaration of martial law last month.

       To them, it was the opposition who had committed insurrection, abusing its majority power at the Assembly？ to repeatedly block Mr. Yoon？’s political initiatives. To them, the opposition’s parliamentary majority ？was invalid because the election last April was rigged. And to them, protecting Mr. Yoon was synonymous with protecting South Korea from “North Korea followers” who have taken root in every corner of their society, from the judiciary to schools to the news media.

       ？South Koreans commonly dismiss such conspiracy theories as little more than online demagoguery spread by right-wing YouTubers with the help of social media algorithms. But amid the country’s entrenched political polarization, they have fueled the turmoil over Mr. Yoon’s situation, driving zealous believers like Mr. Kim to take to the streets in large numbers, calling for the president’s return to office.

       “When I leave home for this rally every day, I tell my wife that this may be the last time she sees me alive, because I am ready to die for my cause,” Mr. Kim said. “This is not just about protecting President Yoon. It’s about saving my country for my descendants.”

       If President-elect Donald J. Trump has a “Make America Great Again” movement behind him, Mr. Yoon has the “taegeukgi budae” ？(literally, “national-flag brigade”). It consists of mostly older, churchgoing South Koreans who enliven their rallies with patriotic songs, a wave of South Korean and American flags in support of their country’s alliance with ？Washington, and vitriolic attacks on the nation’s ？left-wing politicians, whom they fear would ？hand their country over to China and North Korea.？

       Image

       Supporters of Mr. Yoon have camped out for days on the pavement near his home in central Seoul, vowing to block anyone from trying to detain or arrest him.Credit...Chang W. Lee/The New York Times

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