Markets betrayed skittishness on Tuesday as geopolitics and fierce weather rocked Wall Street's late-summer calm.

Major stock indices closed down more than 1 percent Tuesday as traders worldwide reacted to a rapid escalation of the North Korean nuclear crisis, a second powerful hurricane barreling toward U.S. shores in as many weeks and a looming political fight over the increase in the national debt ceiling.

There's also the fact that September is historically the worst month for stocks, the only month that has seen a net negative for the stock market over the past century.

The Dow Jones Industrial Average fell 234 points to 21,753, a decline of 1.1 percent. The tech-heavy Nasdaq and the Standard & Poor's 500-stock index both dropped less than 1 percent.

Financial stocks and insurance companies whose balance sheet could be bludgeoned by another hurricane were among the hardest hit. Conglomerate Berkshire Hathaway, which is heavily bent toward insurance revenues, was down nearly 2 percent. Goldman Sachs Group and JPMorgan were down 3 percent and 2 percent respectively. Bank of America was down more than 3 percent as well.

"A one percent drop or more in the market is recognition that investors are paying attention," said Michael Farr, a Washington-based investment manager. "It's like people in the movie theater. They are locating the exits, but not leaving their seats."

There were signs that investors were seeking asset security as gold prices climbed and U.S. Treasuries strengthened. A widely followed measure of volatility known as the VIX, which has been subdued for much of the year, rose, signalling unease.

Asian markets were mostly up, except Japan, whose Nikkei 225 was down 0.6 percent. European markets were mixed, with Germany's DAX up 0.18 percent and London's FTSE dipping 0.52 percent.

Labor Day weekend saw the double-barreled threat posed by newly christened Hurricane Irma steaming toward Florida on the heels of the devastation of Harvey, which left record flooding in Houston. The drama was heightened as North Korea boasted that it had successfully tested a hydrogen bomb that it could target on the U.S. mainland.

The North Korean test prompted the U.S. envory to the United Nations to say that North Korea was "begging for war." Russian President Vladimir Putin on Tuesday called for talks on North Korea and said U.S. threats of military action could trigger a "global catastrophe."

North Korea, meanwhile, appears to be preparing to test another intercontinental ballistic missile, South Korean officials said late Monday.

The more immediate concern was Irma, which had risen to the strongest Category 5 hurricane status and appeared to be on a path to thread a needle between Florida's Keys and Cuba, at the very least grazing Miami as it headed into the Gulf of Mexico by week's end. By Tuesday, officials in Florida had begun urging people in the storm's path to evacuate.

"It's a scary Category 5, especially on the heels of Harvey," said Chris Gaffney, president of EverBank World Markets.

Steven Hill, a portfolio manager with Foresters Financial, said Irma was one of the headlines his investment team discussed at its Tuesday morning meeting.

"Generally speaking," he said, "a hurricane is going to be good for most of our stocks because of the surge in rebuilding and reinvestments, but with two key exceptions: the first is any stock whose balance sheets or operations are devastated by hurricanes. Stocks who might fit that are reinsurers or chemical plants literally exploding.

"The other exception," said Hill, "is more hurricanes. Irma is only up to letter I. The last major hurricane, Katrina, was followed by Rita and Wilma. If there are another three hurricanes out there this year, I would have to come back and revisit my earlier statements."

Hill said the debt ceiling extension is not likely to be an issue this month because of funding needed for Hurricane Harvey cleanup: "That means I am not looking for September for a shutdown, but December."

Gaffney said glowing world economies and a U.S. market fortified by strong earnings, low inflation and easy money have been able to withstand external pressures such as North Korea, weather and Washington's political rockiness.

"Stock prices are a reflection of future earnings," Gaffney said. "There are huge political risks, but those are hard to price in to stocks. What is the impact of North Korea shooting a missile? You can't really model it. Earnings you can model."