The overall trade deficit fell 9.6 percent to a seasonally adjusted $43.6 billion on falling imports of cars, consumer goods, fuel and semiconductors, US data showed.
But the deficit with China climbed $1.6 billion to $31.7 billion. Trade issues are expected to be a focal point in meetings later this week between US President Donald Trump and Chinese President Xi Jinping.
About 15 minutes into trade, the Dow Jones Industrial Average was down slightly at 20,646.38.
The broad-based S&P 500 slipped 0.1 percent to 2,357.11, while the tech-rich Nasdaq Composite Index advanced 0.1 percent to 5,899.69.
Boeing rose 0.8 percent as it announced that Iran's Aseman Airlines had agreed to buy 30 737 MAX jets for $3.0 billion in its second major deal since sanctions were eased last year.
Ralph Lauren Corporation dropped 1.5 percent after announcing it would book $370 million in one-time expenses for job cuts and store closures, including the shuttering of its Polo flagship store on Fifth Avenue in New York City.