Investing.com - U.S. futures were lower on Friday, struggling to build on Thursday's record close in the S&P 500 after Iran's shooting down of a U.S. surveillance drone stoked fears of war between the two.
U.S. President Donald Trump approved military strikes against Iran on Friday in retaliation, but called off the attacks at the last minute, according to a New York Times report.
Tensions between the two countries have risen since the White House decided to withdraw from the UN-backed 2015 Iran nuclear agreement. The administration most recently accused Iran of last week's attacks on oil tankers in the Persian Gulf, which Tehran denies.
The incident has reminded markets that monetary policy - and specifically the hopes for interest rate cuts and other stimulus from the Federal Reserve and European Central Bank that drove markets higher earlier in the week - is not the only game in town.
Tech-heavy Nasdaq 100 futures slumped 24 points or 0.3% by 6:49 AM ET (10:49 GMT), while Dow futures lost 23 points or 0.1% and S&P 500 futures inched down 4 points or 0.2%.
UnitedHealth Group (NYSE:UNH) was in focus after The Wall Street Journal reported it had agreed to buy health-care payments firm Equian for $3.2 billion.
Tesla (NASDAQ:TSLA) was down 1.3%, while Caterpillar (NYSE:CAT) slipped 1.4% and Carnival (NYSE:CCL) slumped 4.8%, still pressured by a profit warning it issued on Thursday due to weak demand from European customers.
Investors are also likely to keep an eye on Slack (NYSE:WORK), which enjoyed a stellar debut on Wall Street on Thursday, gaining nearly 50% by the market close. However, as the stock was listed without underwriters, it has less protection against possible volatility if market sentiment turns.
In commodities, crude oil gained 0.9% to $57.58 a barrel. Gold futures gained 0.3% to a six-year high of $1,401.55 a troy ounce, while the U.S. dollar index, which measures the greenback against a basket of six major currencies, fell 0.1% to 96.093.