Iran meets with the United States and five other nations in Moscow on Monday over its nuclear program. It is their third session in three months in the latest round of an almost decade-old attempt to answer fears that Iran seeks the bomb. Yet the two sides still have irreconcilable positions, and it is hard to see an ice-breaker towards a deal as they head into talks at the Golden Ring Hotel in the Russian capital.

Iran is under unprecedentedly tough economic sanctions. They are about to get even tougher since both the United States and the European Union will be banning oil sales through Iran's central bank as of July. The goal is to cut Iran's oil revenue by a third. The Iranians want sanctions relief now, in return for any concession they might make about their nuclear work. But the United States wants a gesture first from Iran, and not a small one. It wants the Iranians to stop enriching uranium to 20 percent, which is close to weapons level. The sanctions would begin to be cut back when Iran moved towards suspending all its enrichment work, the bulk of which is to under five percent, the level needed to make fuel for power reactors which generate electricity.

This is all taking place against a background of escalation. Israel is threatening to attack Iran as the Islamic Republic moves towards a dispersal of its nuclear resources and an increase in technological capabilities which would render at least parts of it nuclear work invulnerable to attack from the air. US President Obama has said the window for diplomacy is closing.

But is it? Some make the argument that both Obama and Iran want to kick the can down the road for now. According to this line, Obama wants to avoid, at least until the US presidential election in November, any hint that the Iran situation is getting out of control. Iran is happy to use talks, and even an eventual agreement, to try to reduce sanctions and to parry international pressure in general while it continues to develop its nuclear program.

Whatever the truth to this, the bottom line is that breaking off talks would increase tension. For this reason, both sides have worked at keeping them going. Said one western diplomat: "We want this process to continue: but for that to be possible, we need serious Iranian engagement on our proposals. Let's hope that that's what we find in Moscow."

The Iranians, however, want to redefine the debate. They dispute the challenge to their nuclear work by saying this is an attempt to deny their right to peaceful nuclear technology under the Non-Proliferation Treaty. This is why they want the United States and its negotiating partners Russia, China, Britain, France and Germany to unconditionally recognize their right to enrich uranium. The six nations are not about to do this as they want Iran to cut down on enrichment as a first step to build confidence. This is the gist of the debate after talks in Istanbul and Baghdad. It leaves a wide gulf between the two sides.

So, as usual, expectations are low for talks. The meeting in Istanbul in April had been just a handshake session to resume discussions that had broken off a year and a half earlier. The meeting in Baghdad in May showed just how poor was the communication and trust between the two sides. The Iranians didn't want to discuss reducing their enrichment to 20 percent, which they do for fuel for a research reactor which make isotopes for medical use, until they got what they saw as their basic right to peaceful nuclear work acknowledged.

The success in Baghdad was to agree on a new meeting, significantly in Russia which is Iran's main ally among the six nations with which it is negotiating. Seyed Hossein Mousavian, a former Iranian nuclear negotiator, told me that there is almost no point to negotiations if the six nations are not willing to acknowledge this basic right. He was quoted saying in another interview that the six nations proposal for Iran to stop 20-percent enrichment in return for fuel for its research reactor and spare, now sanctioned parts for its US-made planes was offering "diamond for peanuts." Mousavian told me in a talk at his office in Princeton University, where he is a visiting scholar, that the key is that Iran know that its nuclear rights will be guaranteed. Said Mousavian: "Any step by step or broad package ultimately should include the recognition of rights of Iran for enrichment, and gradual lifting of sanctions. Whether the Obama administration is in a position in an election year to agree, this is the question. If the United States cannot deliver, the Europeans would not be able to deliver. The P5 plus 1 (a name for the six nations negotiating with Iran) would fail."

On the other side, the United States is determined that the step-by-step approach both sides favor would have a first phase in which Iran would give up its 20 percent enrichment. Any sanctions relief, or clarification about the right to enrich, would come later. The US position, largely backed by the P-5 Plus-1, is that giving up 20 percent is not a great concession by Iran. It is something the Iranians should not be doing anyway, especially since they started this enrichment while already under UN Security Council sanctions against their enriching to five percent. Said a Western official: "Iran should come prepared to negotiate seriously and take concrete steps to address the unified proposal laid out by the E3+3 (another name for the P5 plus 1) in Baghdad addressing all aspects of 20 percent enriched uranium, including activities at Fordow (a nuclear site), and enrichment and stockpiling of 20 percent uranium throughout Iran." He added: We all have to remember what we are doing here. The international community's concern is to stop Iran from an acquiring a nuclear weapon. That is what it is fundamentally about."

This is the line-up for the Moscow meeting. There is no shortage of ideas about how the crisis could end. Perhaps Iran will be allowed some enrichment or the United States may step in to help Iran with its civilian nuclear work. The problem is that there is not just mistrust between the two sides but an almost philosophical difference about what nuclear work means and how to guarantee it is not diverted for military purposes.

A first step is needed to turn this vicious circle into a virtual one. And making this first step is where the two sides have so far stumbled. If negotiations go further, it should be clear that talks are not continuing just for talks sake.

This article was published on AOL Defense.