All three major US indexes were lower, with the tech-heavy Nasdaq down the most.
China has vowed that it will not play defense in the escalating trade war, ratcheting up tensions as a new list of items subject to tariffs, including technology and consumer goods was anticipated from Washington.
Consumer discretionary and technology were the biggest percentage losers on the S&P 500, falling 1.0 percent and 0.9 percent, respectively.
"There's the overhang of a potential trade war, which is obviously what's keeping the market suppressed," said Oliver Pursche, chief market strategist at Bruderman Asset Management in New York.
Apple Inc has said the moves could hit a "wide range" of its products. The iPhone maker's shares were down 1.8 percent, providing the biggest drag on the Dow. The stock pared its losses following reports that the United States would spare some of its products in the latest round of tariff actions.
All of the so-called FAANG group of momentum stocks were trading lower. Netflix, Facebook, Amazon and Google-parent Alphabet were down between 0.6 percent and 2.7 percent.
"When you see some of these names that have been up 40, 50, 60 percent year-to-date, taking some profit is the prudent thing to do," Pursche added.
Retailers including Macy's Inc and Kohls Corp dropped, helping pull the S&P 500 retailers index 1.6 percent lower.
The Dow Jones Industrial Average fell 58.47 points, or 0.22 percent, to 26,096.2, the S&P 500 lost 11.74 points, or 0.40 percent, to 2,893.24 and the Nasdaq Composite dropped 81.21 points, or 1.01 percent, to 7,928.84.
Of the 11 major S&P 500 sectors, six were lower.
The CBOE Volatility index, a gauge of investor anxiety, rose 1.02 points, posting its first increase in six sessions.
Twitter fell 3.1 percent, the biggest percentage loser in the S&P 500 technology index, after brokerage MoffettNathanson flagged concerns over rising expenses.
Declining issues outnumbered advancing ones on the NYSE by a 1.28-to-1 ratio; on Nasdaq, a 1.65-to-1 ratio favored decliners.
The S&P 500 posted 33 new 52-week highs and 2 new lows; the Nasdaq Composite recorded 44 new highs and 68 new lows.