That is because all sides have stated their positions ahead of today's talks and their remarks suggest little room for compromise.
The three major EU powers have underlined they want Iran to commit to a sustained -- that is permanent -- suspension of its efforts to master uranium enrichment because it is a "duel-use" process. The process can produce nuclear-reactor fuel or, at high levels of enrichment, material for nuclear bombs.
But Iranian officials say Iran will not give up its right under international treaties to produce its own reactor fuel. They also say Iran has no interest in nuclear weapons.
Iranian President Mohammad Khatami put Tehran's position this way late last month as he vowed Iran's full cooperation with the International Atomic Energy Agency (IAEA), the UN's nuclear watchdog. "We are ready for complete cooperation and [to reach an] understanding with world and also with IAEA to make sure that Iran's [nuclear] activities would not move toward nuclear weapons."
Still, the Europeans and Iranians are talking because the stakes are high. If the Europeans cannot persuade Iran to commit to a significant suspension of its uranium-enrichment-related work, the EU is expected to support Washington's demand that the UN take a tougher stand against Tehran.
The United States is considered likely to call for the governing board of the IAEA to determine Iran is not fully cooperating in opening its nuclear program to international inspectors when it meets in Vienna on 25 November. Washington is expected to also press the IAEA to refer Iran to the UN Security Council for discussion of possible punitive sanctions.
The Europeans see a deal with Iran as the best way to defuse the crisis and they are offering significant incentives to get one. These include offering Iran access to foreign commercial reactor fuel at concessionary prices and Western nuclear technical assistance. Trade incentives are also being discussed.
But analysts say it is highly uncertain whether these incentives are enough for Tehran. Equally uncertain is whether the United States -- which is watching the negotiations but has stopped short of backing them -- would consider such a deal enough to satisfy its own concern over Iran's activities.
Neil Partrick of the Economist Intelligence Unit characterizes Washington's attitude as interested but skeptical. "An awful lot will depend on the ability of IAEA and the Europeans to actually deliver at least a suspension of uranium enrichment by the Iranians," he said. "The impression I have is that the Americans are extremely skeptical about the ability of the Europeans to deliver on this, not least of course because of the seeming failure of the previous understanding that was put into place earlier this year."
The foreign ministers of Britain, Germany, and France won Tehran's agreement late last year to indefinitely suspend activities connected with uranium enrichment in exchange for promises of technical assistance with its commercial nuclear program.
But early this year, Iran accused the three European states of siding with Washington in backing an IAEA resolution "deploring" Iran's lack of cooperation with UN nuclear inspectors.
Tehran subsequently said it is producing large amounts of gaseous uranium and is resuming manufacture of components for high-speed centrifuges which can transform the gas into enriched uranium.
Still, the United States cannot afford to ignore the European effort to strike a "grand bargain" with Tehran. That is because there is no certainty that the 35 member states on the IAEA's board of governors can be persuaded to refer Iran to the Security Council.
Analysts say that IAEA board members like Brazil, China, South Africa, and Sweden -- which have extensive civilian nuclear-energy programs -- may not want to set any precedents that could later be used to curb any programs of their own to manufacture nuclear fuel. That means that there may be many more talks aimed at striking a "grand bargain" in the future no matter what happens in Paris today.
Analyst Partrick told RFE/RL that ultimately the deal the Europeans are trying to reach has to be struck between Tehran and Washington if it is to end the Iranian nuclear crisis. But he said such a deal could be very hard to reach.
"The Iranian version of a grand bargain, as far as it's possible to divine a clear line on this, would be one that involves a significant degree of engagement by the U.S. and the Europeans must be seen as really rather secondary players on this issue, ultimately. And along with that engagement would come some [demands for] clear guarantees about [Iran's] own security. But it's very hard to imagine a U.S. administration of any kind being prepared to make those kind of guarantees to an Iranian regime that remains extremely controversial [in America]," Partrick said.
The British government said this week that it is convinced Washington wants a peaceful solution to the crisis and has no plans for using military force to attack Iran's nuclear facilities. British Foreign Secretary Jack Straw told the BBC 3 November, "The prospect of [military action] happening is inconceivable."