Here's the reported US concession that could clinch the Iran nuclear deal

A nuclear deal with Iran looks like a certainty, with one observer of the talks currently in Vienna telling Business Insider that there is a "99.9%" chance that the negotiations won't go past July 14th.

According to New York Times Tehran correspondent Thomas Erdbrink, Iranian state TV has announced that the text of the deal has been completed and only needs to be proofread before the agreement can be finalized. State media agency Fars News also reported that the final document is around 100 pages long.

According to the Associated Press, the deal will be announced early on July 14th.

Resolution of the talks between the five permanent members of the United Nations Security Council and Germany (the so-called P5+1) and Iran has apparently been delayed by a single issue: the lifting of a UN arms embargo implemented over the course of 2007 and 2008.

Iran wants the embargo lifted, as do P5+1 members China and Russia. According to Politico, the discussion in Vienna is over "how" to lift the embargo.

Meanwhile, the Obama administration would face domestic opposition to facilitating arms flows to a US-designated state sponsor of terrorism by lifting an embargo that's arguably unrelated to the nuclear issue.

The P5+1 has arguably made deeper concessions than the lifting of the arms embargo, which adds to the irony of a prospective deal meant to stem the spread of nuclear weapons hinging on a matter relating to conventional arms.

The installation of 1,000 centrifuges at the illicit Fordow nuclear facility, the exemption of Iran's potentially nuclear-capable ballistic missile arsenal from the nuclear talks, and a retreat from international insistance on full disclosure of Iran's previous nuclear weaponization activities are all more significant negotiating achievements for Iran's clerical regime.

Other, more important concessions have already been agreed to. Iran could leave the arms embargo alone and still emerge with a fairly favorable agreement.

At the same time, the debate over the arms embargo isn't as much of an aberration as it might seem, and is in some ways a reflection of how the nuclear talks have often progressed.

The latest round of negotiations began on June 27th, with an initial June 30th deadline, meaning that US Secretary of State John Kerry and his team have now been in Vienna for over 2 weeks.

The incentive to wrap up an agreement is strong on the US side, especially in light of the time and political capital that president Barack Obama and his administration have poured into a potential deal. In contrast, the Iranians have the backing of P5+1 members China and Russia in their effort to get the embargo lifted.

It looks like the negotiating dynamics are lining up in Iran's favor, and Tehran is naturally pressing its advantage.

Compromise over the arms embargo could echo other P5+1 workarounds

On uranium enrichment, the P5+1 agreed to a phased lifting of limitations over the life of the deal, with most enrichment restrictions disappearing after 10 years. Iran also gained the ability to enrich uranium at the heavily armored Fordow facility at year 15.

On sanctions, Iran will reportedly gain the immediate repeal of UN sanctions authorizations days after a deal is signed, but will have to wait a period of months until US measures are suspended.

And on inspections, Iran will initially agree to "provisional" rather than binding acceptance of the Non-Proliferation Treaty's additional protocol and will reportedly be able to manage inspector access to military sites.

All of these formulations are substantively concessions to Iran. Tehran will get expanded enrichment and full sanctions relief over the life of the deal, along with a certain amount of influence over the verification process.

These compromises are arguably necessary trade-offs for gaining Iranian approval of the aspects of a deal that have the most direct bearing on the country's ability to accumulate bomb fuel - Iranian concessions such as modifications to the Arak heavy water reactor in addition to restrictive centrifuge and uranium stockpile caps.

And now a similar trade-off seems to be unfolding around the arms embargo. According to Politico, the P5+1 and Iran are now discussing how the embargo can be repealed, with the US "insisting on a slower phase-out."

White House press secretary Josh Earnest would not directly address whether the embargo was still up for discussion during a July 13th press conference, meaning the White House isn't denying that there's discussion of relieving the embargo as part of a deal.

The Obama administration may hope that the phased fulfillment of yet another Iranian negotiating objective can preserve a wider nuclear agreement designed to keep Iran a year away from building a nuclear weapon for more than a decade.

But despite reports that an agreement will be announced on July 14th, the negotiations have already dragged on longer than most observers anticipated.

And in a sensitive arms control negotiation between two long-time geopolitical foes, nothing is agreed to until everything is.