NEW YORK (CNN/Money) - Judging from Monday's market action, investors have decided the world's "moment of truth" will set stocks free.

Coming back from a slide into the red at the opening bell and a pall that had sent overseas markets stumbling, U.S. stocks staged a huge rally. The Dow Jones industrial average finished the day up 282 points, at its best close since January. The Nasdaq's 3.9 percent rise put it further into the positive column for the year.

The catalyst? It appeared to be the United States' decision not to seek a United Nations Security Council resolution backing war with Iraq. Coupled with the U.S.-recommended evacuation of U.N. personnel from Iraq, the implication was clear: The U.S. administration and its allies have turned their backs on diplomacy and war could begin any day now.

President Bush was set to address the country in a speech at 8 p.m. ET.

"We're going to war," said Jim Volk, director of institutional trading at D.A. Davidson. "I don't know if there will be bombs on the ground by the time he starts talking or if he'll wait a couple of days to make sure all the inspectors are out of there, but we're going."

In rallying stocks, traders appeared to be pulling a page out of the 1991 Gulf War playbook. In the month following the beginning of allied forces bombing on Jan. 17, 1991, the Dow traveled 17 percent higher. Early on in the war, investors had quickly come to see that Saddam Hussein's military was not as strong as they had feared, and the war would not last long.

Using that experience as a guide, some traders are apparently trying to get into the market early now, fearful not so much that the war could go badly as that there could be a rally they would miss out on.

"We're going through the roof here on the expectation of a 48-hour war," said Mizuho Securities USA futures strategist Phil Ruffat. "If the war is over quickly, you might see a 1,000-point rally on the Dow -- that's what the consensus is. Obviously, it's one of those things which might turn true before it even happens, which is dangerous."

Indeed, some Wall Streeters speculated that with so many investors having bought stock in anticipation of a war rally, there will be a mass of stocks for sale when war starts.

If Monday's rally elicited anything on Wall Street, it was head-scratching.

Sure, you could paint a pretty explanation for the move higher. You could say that it was about certainty, for instance, that after months of not knowing what was coming next, investors finally had, in the surety of war, a course for action. But the market rallied only four days earlier, on Thursday -- supposedly because war was going to be delayed.

Some also cited "short covering." Investors who had sold shares short in hopes of the market going down were buying them back in an effort to close out positions and "be flat" ahead of war. But while that may have been part of what was going on, volume was far too heavy for that to be any more than a partial explanation. Real investors appeared to be in there buying.

"I can't figure it out," Putnam Lovell head of U.S. equities Jack Baker said of Monday's action. "You've got to go somewhere else to find the answer to this."