NEW YORK — Financial markets can be a game of nuance, one the Federal Reserve attempts to play with finesse by keeping investors guessing on its next move in interest rate policy.

So while there's plenty of disagreement over President Bush's decision to keep buying oil for the nation's emergency supply rather than selling some to help lower fuel prices, it's not clear why the administration has chosen to play its hand so openly.

The issue isn't whether the nation's emergency oil supply should be actually used or not. Let the politicians decide that. Instead, the question is whether it was wise for Bush to be so definitive in declaring that he won't tap the strategic reserve to influence the energy market.

For obvious reasons, the primary purpose of the "strategic petroleum reserve" is to provide a ready stash of oil as a hedge against unexpected disruptions in the flow of foreign oil, whether the result of violence in the Middle East, or the type of labor discord that crippled Venezuelan production in 2002 and 2003.

That primary purpose is why, since it was created in 1975 in reaction to the Arab oil embargo, the strategic reserve is rarely tapped.

But rarely isn't the same as never. The reserve was tapped to combat rising oil prices by the first President Bush and then by President Clinton, raising the prospect that it could happen again.

That was enough to make energy traders mindful of potential U.S. market intervention in their calculations. Now, however, the second Bush administration has made it clear it won't turn to the reserve despite record oil prices.

Traders know that compared with other sources of crude, the strategic reserve can pump a fairly rapid infusion of oil to the market. Because the stash is so large, because it doesn't need to make a 40-day journey to get here from the Mideast, and because the oil is of a higher quality that can be refined more quickly, any decision to sell oil from the reserve could send prices sliding.

As a result, the reserve has come to represent a wild card in the energy market, not unlike the levers on money supply that the Fed can manipulate at any time to adjust interest rates. The debate is how best to use that power, if at all.

"Most people would not want to see (the reserve) used as a pricing mechanism, but to be used when there's a legitimate threat to the U.S. economy," said Larry Goldstein, president of the Petroleum Industry Research Foundation in New York, declining to offer his own position on the question. "Now, we can also argue that at current price levels the price is harming the economy."

It would be naive, however, to suggest that the very decision not to intervene won't have an impact all its own. Just as the Fed needn't actually turn its monetary dials to influence the markets, it doesn't take an actual decision to sell oil from the strategic reserve to provide some downward pressure on prices.

In fact, while Fed officials often signal the market with public remarks, all the White House needs to do is say nothing. The point is to merely leave the appearance that all options are available even if internally there's not the slightest chance the administration will waver in its resolve not to tap the reserve in a nonemergency.

Since markets hate uncertainty, as the adage goes, even a vague risk of additional supply hitting the market can be enough to make energy traders think twice about bidding the price of oil ever higher.

In the past, those fears really started percolating whenever the price pushed within range of $40 a barrel, the level at which the first Bush and Clinton took action, providing at least one downward pressure on prices.

But this time around, with prices now setting record highs above $42, traders have had no such distraction, confident from the administration's very public, very definitive insistence that its trump card won't be played.

Instead, traders can bet that the White House, if anything, will ensure strong demand at these elevated prices by continuing to stockpile crude, buying more than 100,000 barrels a day on the open market, also in a very public, insistent manner.

"I was never against beefing up our oil supplies," said Fadel Gheit, senior energy analyst at Oppenheimer & Co. "But why disclose what we put in the strategic petroleum reserve? Why spell it out? In whose interest are you putting this information out?"

Exacerbating the situation, other major nations have been adding to their own stockpiles, mindful that the administration's continuing buildup can be seen as a very pessimistic risk assessment for the oil market by the powerful player who should know best.

"This excessive buying has been going on in the oil market for well over a year as a result of the U.S. leading the charge, sending the wrong message to the market," Gheit said.

With so many other uncertainties playing on the market, it's hard to assert that a different message from the Bush administration might have produced a more positive outcome with gasoline prices ranging closer to $1.50 a gallon than $2.50 a gallon.