US stands apart as G-20 summit stumbles on trade, climate

European Council's President Donald Tusk, right, leaves the presidential palace after meeting Argentina's President Mauricio Macri in Buenos Aires, Argentina, Thursday, Nov. 29, 2018. Leaders from the Group of 20 industrialized nations will meet in Buenos Aires for two days starting Friday. (AP Photo/Sebastian Pani)

From left, President of Brazil Michel Temer, President of Russia Vladimir Putin, President of South Africa Cyril Ramaphosa, President of China Xi Jinping, and Prime Minister of India Narendra Modi pose for a photo at the G20 summit in Buenos Aires, Argentina, Friday. (Mikhail Klimentyev, Sputnik/Kremlin Pool Photo via AP)

Russian President Vladimir Putin attends the G20 summit in Buenos Aires, Argentina, Friday, Nov. 30, 2018. Leaders from the Group of 20 industrialized nations are meeting in Buenos Aires for two days starting today. (Mikhail Klimentyev, Sputnik, Kremlin Pool Photo via AP)
Argentina's President Mauricio Macri, right, welcomes Italy's Prime Minister Giuseppe Conte to the start of the G20 summit in Buenos Aires, Argentina, Friday, Nov. 30, 2018. Leaders from the Group of 20 industrialized nations are meeting in Buenos Aires for two days starting today. (AP Photo/Ricardo Mazalan)
President Donald Trump arrives for the opening of the Group of 20 summit at the Costa Salguero Center, in Buenos Aires, Argentina, Friday, Nov. 30, 2018. Leaders from the world's leading economies were invited to the G20 summit to discuss development, infrastructure and investment. As the gathering officially kicks off Friday, those themes seem like afterthoughts, overshadowed by contentious matters from the U.S.-China trade dispute to the conflict over Ukraine. (AP Photo/Gustavo Garello)

BUENOS AIRES, Argentina — The U.S. has been blocking progress at the Group of 20 summit on fixing world trade rules, fighting climate change and tackling migration, according to European officials involved in the discussions.