A lockdown in Shanghai marks another potential setback for China’s export machine, reigniting concerns over the risk of renewed disruption to global supply chains pummeled by the pandemic and war in Ukraine . Authorities imposed a two-stage lockdown on China’s most populous city on Monday, the latest reverberation from the country’s zero-tolerance Covid-19 strategy that is facing its toughest test yet from the highly contagious Omicron variant. Continue reading your article with a WSJ membership View Membership Options