Wall Street stocks dipped early Monday after US President Donald Trump announced tariff actions on Brazil and Argentina and China retaliated for a US bill supporting protesters in Hong Kong.
Trump said he was reinstating tariffs on steel and aluminum from the South American countries due to a devaluation of their currencies. The United States had previously exempted some countries, including Argentina and Brazil, which agreed to quotas on the metals.
Meanwhile, China suspended US warship visits and sanctioned American NGOs after Trump signed into law a congressional measure supporting pro-democracy protesters in Hong Kong.
Some analysts rated the Chinese measures as mostly symbolic but said they were potentially important in light of ongoing trade talks between Washington and Beijing.
About 15 minutes into trading, the Dow Jones Industrial Average stood at 28,038.17, down 0.1 percent.
The broad-based S&P 500 dropped 0.2 percent to 3,135.43, while the tech-rich Nasdaq Composite Index shed 0.4 percent to 8,633.53.
US stocks are still within shouting distance of all-time highs following records last week that were fed by optimism over the US-China trade talks, upbeat expectations for the holiday shopping season and moves by the Federal Reserve to cut interest rates and loosen monetary policy.
Key events this week include updates on the manufacturing and services sector, as well as the November jobs report.