Chinese Vice Premier Liu He, at right welcomes United States Trade Representative Robert Lighthizer, center and Treasury Secretary Steve Mnuchin, at left before holding talks at the Xijiao Conference Center in Shanghai. China, July 31, 2019. Ng Han Guan/Pool via REUTERS

SHANGHAI (Reuters) - U.S. Trade Representative Robert Lighthizer and Treasury Secretary Steven Mnuchin shook hands with Chinese Vice Premier Liu He before beginning trade talks in Shanghai on Wednesday in a bid to end a year-long trade war.

U.S. President Donald Trump on Tuesday warned China against waiting out his first term to finalize any trade deal, saying if he wins re-election in the November 2020 U.S. presidential contest, the outcome will be worse for China.