Pro-Palestinian protesters have blocked Pride marches in several cities across the country, including Boston, Philadelphia and Denver. Rainbow flags typically go unrivaled at the nation’s LGBTQ Pride marches. But this year, another symbol has played an outsize role in the annual celebrations: the Palestinian flag. Waving red, white, green and black, hundreds of pro-Palestinian activists have disrupted some of the nation’s largest Pride parades this month in protest of the Israel-Hamas war and the tens of thousands of deaths and untold suffering it has caused since October. In Philadelphia, pro-Palestinian demonstrators temporarily blocked the city’s June 2 march, confronting participants...