Stock futures moved slightly lower on Tuesday as markets continued to struggle for direction in a short holiday week. 

S&P 500 futures were down 0.12%, Dow Jones Industrial Average futures fell 0.06%, and Nasdaq futures slipped 0.09%. 

Markets have been in a holding pattern in recent days, stuck between worries over rising geopolitical tensions and hope over the upcoming first-quarter earnings season. Nerves over geopolitical uncertainty continued on Tuesday as investors assessed the U.S.'s increasing involvement in Syria and North Korea. 

The U.S. launched about 60 cruise missiles at a Syrian airbase last Thursday, the first direct intervention in Syria's long-running civil war. The Trump administration approved the strike in retaliation to a chemical attack from the Assad regime last week that killed dozens of civilians. 

North Korea said 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, the Associated Press reported. 

Big banks are set to kick off the first-quarter reporting period this week. Citigroup (C - Get Report) , JPMorgan (JPM - Get Report) and Wells Fargo (WFC - Get Report) will report their performance over the three months to March 31 on Thursday, the final day before Wall Street takes a three-day Easter weekend.

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.

Hopes are high for another period of growth for companies in the S&P 500. Operating income is expected to increase more than 9% during the first quarter, according to FactSet, the fastest pace in just over five years. Another period of growth would mark the third straight quarter of earnings gains in a row.

United Airlines (UAL - Get Report)  is suffering the fallout from an incident over the weekend in which a passenger was violently dragged from the aircraft for not voluntarily giving up his seat. The elderly doctor had been randomly picked to give up his seat on an overbooked flight to accommodate United staff. When he refused, airport police dragged him from the airplane, bloodying him in the process. The incident, filmed by several passengers, went viral on social media platforms and put United on defense.

CEO Oscar Munoz issued a letter late Monday that defended his employees, saying the passenger was being "disruptive and belligerent." While Munoz said he was "upset" to see and hear what happened, "our employees followed established procedures for dealing with situations like this."

Investors grew concerned over the public relations crisis, particularly heading into the busy summer months. United had already been in the news in recent weeks for refusing to board two teenagers wearing leggings that violated United's dress code.

United shares fell 3% in premarket trading. 

Fellow airline American Airlines (AAL - Get Report) added nearly 1% in premarket trading after reporting that March traffic fell 1.2%, while capacity slipped 0.9% to 23 billion available seat miles. The load factor fell to 81.5% from 81.7% a year earlier. 

Qualcomm (QCOM - Get Report)  moved slightly lower on Tuesday morning after filing a counterclaim to charges against it that Apple ( AAPL - Get Report) made in January. Qualcomm said the iPhone maker "breached agreements" with the chipmaker and "encouraged regulatory attacks on Qualcomm's business in various jurisdictions around the world by misrepresenting facts and making false statements." 

Apple had accused Qualcomm of overcharging for chips and refusing to pay about $1 billion in promised rebates. The lawsuit came days after the Federal Trade Commission accused the chipmaker of engaging in anticompetitive behavior to maintain dominance over the market.

Apple is a holding in Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio. Want to be alerted before Cramer buys or sells AAPL? Learn more now.

RetailMeNot (SALE) rocketed 50% higher in premarket trading after agreeing to be acquired by privatelybowned Harland Clarke Holdings for $11.60 a share. The deal values the coupons website at a roughly 50% premium to its Monday close. Harland will pair RetailMeNot with its other coupon business Valassis Communications, which also deals in mail and print. 

Whole Foods (WFM) jumped 10% late Monday afternoon after activist investor Jana Partners built a 9% stake and was pushing for board changes. The fund said in a securities filing that it wants to see Whole Foods initiate a review of strategic alternatives, adding that the grocery store chain has been "unwilling to engage in discussions with third parties" about M&A alternatives.

Supervalu (SVU)  climbed 6% after the wholesale distributor said that it will be acquiring Unified Grocers in a $375 million deal. Supervalu will pay $114 million in cash for 100% of the outstanding stock of the California-based food distributor. Supervalu will assume $261 million in debt. The deal is expected to close this summer.

Yelp (YELP - Get Report) was upgraded to overweight from sector weight at Pacific Crest. Analysts also set a $43 price target, an increase of more than 31% from current levels. Pacific Crest said competitive concerns over Yelp's "relevance are overdone."

Goldman Sachs has reaffirmed its buy rating on Walt Disney (DIS - Get Report) stock and increased its 2017 earnings per share estimates following the success of its latest theatrical release, Beauty and the Beast. Goldman has also added Disney to its Americas Conviction Buy list.

The U.S. economy is moving along at a healthy pace with little need for acceleration from the central bank, Federal Reserve Chair Janet Yellen said on Monday evening. Speaking at the University of Michigan, Yellen said that the Fed is "allowing the economy to kind of coast and remain on an even keel to give it some gas, but not so much that we're pressing down on the accelerator." The central bank raised rates by 25 basis points at its March meeting, the third increase since 2008.