Stocks closed lower Wednesday as markets grappled with confusion about U.S. President Donald Trump's next moves with Russia, Syria and North Korea. 

The S&P 500 was down 0.38%, the Dow Jones Industrial Average fell 0.29%, and the Nasdaq slipped 0.52%. Manufacturing and materials industries led stocks lower, with Caterpillar (CAT) - Get Report down 2.3% and Boeing (BA) - Get Reportfalling 1.4%.

Markets awaited an outcome from U.S. Secretary of State Rex Tillerson's visit to Moscow, where he addressed Russia's continued assistance of Syrian President Bashar al-Assad. Tillerson met with Russian President Vladimir Putin at the Kremlin for about two hours in an atmosphere charged by White House claims that Moscow tried to cover up Syria's deadly chemical attack on April 4 in order to protect Assad.

Tillerson emphasized the Trump administration's stance that "the reign of the Assad family is coming to an end," in a press conference with Russian Foreign Minister Sergey Lavrov. Lavrov and Tillerson agreed to investigate the chemical weapons attack in Syria, though tensions remained apparent.

"We have seen very alarming actions recently with an unlawful attack against Syria," Lavrov said, referring to the U.S. airstrike. "We consider it of utmost importance to prevent the risks of replay of similar action in the future."

The U.S. last week launched 60 cruise missiles at a Syrian airbase, a move President Trump approved after Assad's regime killed dozen of civilians in the chemical attack.

Also on investors' minds is the strong language used by Trump on North Korea. In a Twitter post, Trump said, "North Korea is looking for trouble. If China decides to help, that would be great. If not, we will solve the problem without them!"

North Korea said Tuesday there could be "catastrophic consequences" after the U.S. ordered the USS Carl Vinson aircraft carrier and its battle group to waters off the Korean Peninsula.

"This has been a period in which the equity markets have flattened a little bit after the euphoria of the post-election period and the anticipation of many of the promised elements of the new administration, namely fiscal measures and tax cuts, infrastructure spending and rollbacks of regulation," Bill Northey, U.S. Bank's private client group chief investment officer, said in a phone interview. 

Gold closed 0.3% higher at $1,278.10 an ounce, the second daily increase in a row, as investors moved into safe havens to guard their wealth from market volatility.

Crude oil settled 0.5% lower at $53.11 a barrel after the Energy Information Administration's weekly status report showed that U.S. crude oil inventories declined by 2.2 million barrels last week, the first decline in a month. Gasoline fell 3 million barrels and distillates dropped by 2.2 million barrels.

OPEC said in its monthly oil report on Wednesday that production decreased by 153,000 barrels a day to an average of 31.93 million barrels. OPEC increased its forecast for the U.S. oil supply by 200,000 barrels a day to 540,000 barrels a day.

United Airlines (UAL) - Get Report  continues to deal with fallout from video of a passenger being violently dragged off an airliner after refusing to give up his seat to carrier employees who needed seats on the full plane in order to meet the carrier's flight schedule. 

CEO Oscar Munoz issued a second apology Tuesday, saying, "I continue to be disturbed by what happened on this flight, and I deeply apologize to the customer forcibly removed and to all the customers aboard. No one should ever be mistreated this way."

Tuesday's statement came after Munoz defended his employees in a letter Monday, saying the 69-year-old doctor was being "disruptive and belligerent."

United shares fell 1.1% on Wednesday after rising in earlier trading. 

Delta Air Lines (DAL) - Get Report  reported first-quarter adjusted earnings of 77 cents a share, topping forecasts by 2 cents. Delta said traffic in the first quarter rose 0.5% and capacity dipped 0.5%. The stock fell 0.5%. 

Whole Foods (WFM) shares jumped 1.7% in trading after Bloomberg reported that Amazon (AMZN) - Get Report  considered taking over the grocer last year, but decided against making a move. The report follows news that activist investor Jana Partners built a 9% stake in Whole Foods ans is pushing for board changes.

Akzo Nobel (AKZOY) accused one of its biggest shareholders of planning to share price-sensitive information with rival PPG Industries (PPG) - Get Report and rejected calls for the dismissal of its chairman amid an increasingly hostile takeover showdown.

Fastenal (FAST) - Get Report shares dropped 8.1% Wednesday as the industrial and construction supplies company posted first-quarter earnings of 46 cents a share, meeting estimates. 

Neurocrine Biosciences (NBIX) - Get Report shares rose 24.9% after the Food and Drug Administration approved its drug Ingrezza to treat tardive dyskinesia, the only medication available for the disease.

Shares of BlackBerry (BBRY) popped 16% after the company announced it was awarded $814.9 million of royalty payments in an arbitration against Qualcomm (QCOM) - Get Report . Qualcomm shares fell 2.9%. 

Earnings will kick into high gear on Thursday as Citigroup (C) - Get Report , JPMorgan (JPM) - Get Report and Wells Fargo (WFC) - Get Report are scheduled to issue their quarterly reports.

Citigroup and Wells Fargo are holdings in Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio.Want to be alerted before Cramer buys or sells C or WFC? Learn more now.

Tractor Supply (TSCO) - Get Report fell over 8% after the company said it expected same-store sales to fall 2.2% in the first quarter and that profit would miss estimates by as much as 8 cents. The company will report final first-quarter results on April 26.

As for U.S. economic data, import prices in the U.S. fell 0.2% in March, matching economists' estimates. Import prices rose 0.2% in February. Export prices rose 0.2% in March, topping expectations.