The Dow Jones industrial average fell in early trading and then rose as much as 35 before pulling back again late in the day. Analysts said indecisive investors weren’t willing to make major commitments given the renewed political uncertainty, but also given the improving health of the U.S. economy.

“Investors are very nervous about continued terrorist activity, but at the same time, they are showing more confidence in the economy and the equity market,” said Peter Dunay, chief market strategist at Wall Street Access. “So we have a little battle of the pros and cons here.”

The Dow closed down 71.04, or 0.7 percent, at 9,619.42, having declined in four of the previous five sessions.

The broader market also finished lower. The Nasdaq composite index fell 17.73, or 0.9 percent, to 1,881.92. The Standard & Poor’s 500 index declined 8.79, or 0.8 percent, to 1,033.65.

In Turkey, two truck bombs exploded outside London-based HSBC and the British consulate, killing at least 25 people and wounding nearly 400. The explosions, which came during President Bush’s trip to Britain, were blamed on the al-Qaida terror network.

Until this week, terrorism had receded as a factor in stock trading, but the bombings of two synagogues in Turkey over the weekend and today’s attacks reminded markets around the world of the danger that terrorist networks still pose.

Perhaps adding to the uneasiness on Wall Street today was the brief evacuation of the White House after birds or possibly atmosphere disturbances triggered a false radar reading, which was initially thought to be an unauthorized plane flying near the White House.

But the economic news lent support to the market, and enabled the major indexes to move briefly into positive ground.

The Labor Department reported that new jobless claims fell by a seasonally adjusted 15,000 to 355,000. The reading, which beat economists’ estimates, was the seventh straight week that claims have been below 400,000.

And the Conference Board said its Index of Leading Economic Indicators, the widely watched economic forecasting gauge, increased 0.4 percent to 113.6 last month compared to a flat reading in September. Analysts were expecting a more modest 0.2 percent rise.

“It’s all about the unrest as far as the terrorism,” said Todd Clark, head of listed equity trading at Wells Fargo Securities. “It’s given people the excuse to stay away.”

He added that many investors, nervous that stock valuations might be a bit high after several months of advances, are being cautious to make sure they can end the year with gains.

Schering-Plough Corp. fell 72 cents to $15.28 after the drug company said its Polish subsidiary is being investigated by federal regulators.