By Jeffrey Goldberg Dec 3, 2013 5:11 PM ET

The interim nuclear agreement between the Great Powers (such as they are) and Iran is creating a lot of anxiety for people who support the deal, because not much proof has been offered to suggest that it will actually work. And by “not much proof,” I mean, “no proof.”

Why support it, then? Because, so far, the remote possibility that this agreement will lead to the denuclearization of Iran beats the alternative: military action by the U.S. or, worse, by Israel. All options should be on the table, but, really, the military option could be disastrous.

Here are six reasons to be worried about the strength of this interim deal. These worries have to do with the particulars of the agreement, but also with the reality of the Iranian nuclear program, which is already quite well developed.

1. The deal isn’t done. Remember the photos from Geneva of smiling foreign ministers slapping backs and hugging in celebration of their epic achievement? Well, nothing was actually signed. The deal is not, as of this moment, even operational.

U.S. State Department spokeswoman Jen Psaki was asked a question last week about when the deal might actually take effect. “The next step here is a continuation of technical discussions at a working level so that we can essentially tee up the implementation of the agreement. So that would involve the P5+1 -- a commission of the P5+1 experts working with the Iranians and the IAEA," shesaid, referring to the permanent members of the United Nations Security Council plus Germany and the International Atomic Energy Agency. "Obviously, once that’s -- those technical discussions are worked through, I guess the clock would start.”

Focus on those last words for a second: “I guess the clock would start.” Do words like those make you worried, or is it just me? What this means is that Iran, at this moment, is still not compelled to freeze any of its nuclear program in place. I’m not sure why American negotiators would leave Geneva without having a fully implemented agreement. I understand that the technical hurdles to implementation are daunting. But equally daunting is the realization that the Iranians are going about their business as if they’ve promised nothing.

2. Momentum for sanctions is waning. It's true that the economic relief the Iranians will receive in this deal is modest, but it is also true that many nations, many companies and the Iranians themselves are seeing this agreement as the beginning of the end of the sanctions regime. Iran is already making a push to recapture its dominant role in the Organization of the Petroleum Exporting Countries. U.S. officials believe they can hold the line on sanctions, but it is reasonable to assume that they will come under increasing pressure from countries such as South Korea, Japan, India and China, which could very easily convince themselves that Iran is preparing to act in a more responsible manner (after all, it replaced its snarling, Holocaust-denying president with a smiling, savvy president) and should be reopened for business.

3. The (still unenforced) document agreed upon in Geneva promises Iran an eventual exit from nuclear monitoring. The final (theoretical) deal, the document states, will “have a specified long-term duration to be agreed upon,” after which the Iranian nuclear program “will be treated in the same manner as that of any non-nuclear weapon state” that is part of the Non-Proliferation Treaty. From what I’m told, the U.S. hopes this eventual agreement, should it come to pass, would last 15 years; the Iranians hope to escape this burden in five. After the agreement loses its legal force, Iran could run however many centrifuges it chooses to run. This is not a comforting idea.

4. The biggest concession to the Iranians might have already been made. Although it is the West’s position that it has not granted Iran the so-called right to enrich, the text of the interim agreement states that the permanent deal will “involve a mutually defined enrichment program with mutually agreed parameters.” Essentially, Barack Obama's administration has already conceded, before the main round of negotiations, that Iran is going to end up with the right to enrich. Realists would argue that Iran will end up with that “right” no matter what, but it seems premature to cede the point now.

Understanding Iran's Uranium Enrichment

5. The Geneva agreement only makes the most elliptical references to two indispensable components of any nuclear-weapons program. The entire agreement is focused on the fuel cycle, but there is no promise by Iran in this interim deal to abstain from pursuing work on ballistic missiles or on weaponization. A nuclear weapons program has three main components: the fuel, the warhead and the delivery system. Iran is free, in the coming six-month period of the interim deal, to do whatever it pleases on missiles and warhead development.

6. The Iranians are so close to reaching the nuclear threshold anyway -- defined here as the ability to make a dash to a bomb within one or two months from the moment the supreme leader decides he wants one -- that freezing in place much of the nuclear program seems increasingly futile. When asked this week by al-Jazeera about the impact of sanctions, the very smart Iranian foreign minister, Mohammad Javad Zarif, said, “When sanctions started Iran had less than 200 centrifuges. Today Iran has 19,000 centrifuges so the net product of the sanctions has been about 18,800 centrifuges that has been added to the Iran's stock of centrifuges, so sanctions have utterly failed.”

Zarif is wrong in one regard: Sanctions placed the Iranian economy under enough pressure to force its negotiators to Geneva. But he is right when he asserts that Iran moved closer to nuclear breakout at the same time it was suffering under what Obama has long called “crippling sanctions.”

One of Israel’s most prominent experts on the Iranian nuclear program, a former military intelligence chief named Amos Yadlin, said this week that “Iran is on the verge of producing a bomb. It’s sad, but it’s a fact.” Yadlin suggested that no one, and no agreement, can stop Iran from reaching the nuclear threshold. I fear he is right.

There are, of course, compelling arguments to be made -- and ones that have already been made -- by the Obama administration and its foreign partners in favor of this deal. Because I am both fair and balanced, I will do my best to represent those arguments in a coming post.