A deal struck by European powers to suspend Iran's nuclear enrichment activities - blessed yesterday by the International Atomic Energy Agency - puts a few more teeth in international efforts to inhibit Iran from ever developing a nuclear bomb.
In that sense, the deal is a victory for attempts to stop the spread of nuclear weapons and for global security. But deal supporters and skeptics alike will be watching carefully over coming weeks to see if the accord reached between Iran and Britain, France, and Germany takes hold - or unravels in the same way as earlier efforts to curtail Iran's ambitions diplomatically.
"Because of the specificity of this [agreement], if it holds, it should provide us with more security, so that's a good thing," says Paul Kerr, a nonproliferation analyst at the Arms Control Association in Washington. "But trends were not positive before. And even now there's enough ambiguity that ... we'll have to live with a certain amount of uncertainty for the foreseeable future."
The key question now, some analysts say, is how the United States responds to the deal - and whether it acts to support it or kill it.
"This deal freezes Iran's programs and gives us space to negotiate a permanent end to the programs," says Joseph Cirincione, head of the nuclear nonproliferation project at the Carnegie Endowment for International Peace in Washington. "The US and only the US can provide the security guarantees Iran needs to permanently end its nuclear programs."
The US, he adds, "can kill the deal by sitting by passively. This will not work without US participation."
In language that was considerably weaker and more conciliatory than what the US had sought, the International Atomic Energy Agency (IAEA) welcomed what it called Iran's "voluntary, nonlegally binding, confidence-building" agreement to suspend uranium enrichment activities. The international proliferation watchdog is charged with verifying that the accord is not broken.
The IAEA said yesterday it had ascertained that Iran's enrichment work, including 20 disputed centrifuges (or enrichment processors) that the Iranians had sought to leave outside the accord, had been suspended.
Under terms of the deal, Iran will allow the IAEA to put the country's enrichment and reprocessing activities under surveillance. But instead of being sealed, the machinery will be placed under camera surveillance. In addition, Iran has agreed to cease all "testing" involving the enrichment facilities - a change from earlier demands that it cease "research and development" activities.
The Iranian government insists its nuclear program is for peaceful, energy-generating purposes only. The US doubts that's true, and the Europeans have been worried enough to press through diplomatic channels for agreements.
US officials note that a year-old accord reached between the IAEA and Iran has not stopped nuclear development by a country officially listed by Washington as a state sponsor of terrorism. The US believes the international community may be capable of curtailing activity at Iran's known nuclear facilities, but it suspects there is more to Iran's program than meets the international eye.
Recently the CIA said in a fresh assessment that IAEA monitoring and inspections can prevent Iran from proceeding with enrichment work at known facilities - but the question mark was what facilities Iran may have that the world doesn't know about.
The US had wanted to take the issue of Iran to the United Nations Security Council to seek sanctions as a tougher means of stopping its nuclear program. But the three European countries - two of whom (Britain and France) are permanent members of the Security Council - agreed not to support Washington's efforts in exchange for the suspension of enrichment work.
In addition, the Europeans will begin negotiating with Iran within the next few weeks for the economic and political rewards that are to be part of Iran's suspension agreement.
Some analysts already see the harbinger of a breakdown in the agreement: The Europeans and Iranians are giving conflicting assessments of what the incentives should include and how soon the rewards should begin. European officials speak of a "sustained" and verified suspension before serious talks begin, while the Iranians have spoken of a "brief" suspension to test international seriousness.
US officials will be watching Iran's compliance with the accord as well as European progress on keeping the suspension intact while it negotiates. They may plan to keep up the rhetorical heat until the next planned meeting of IAEA governing countries in March, which would provide the venue for a public airing of how yesterday's deal is faring.
"The US will continue to make public statements of skepticism, of suspicions of secret facilities. They'll make noise to keep the pressure on," says Mr. Kerr. But it will be "wait-and-see" mode until March, he says - unless the deal shows signs of unraveling before then, "in which case they'll be back to demands to get this to the Security Council."
Some observers have seen the international wrangling over Iran as an application of the classic "good cop-bad cop" strategy, with the Europeans offering the carrots and encouraging words, while the US holds up the stick.
But in another sense, the Iran saga offers a window into a kind of international competition between two visions for dealing with "rogue" nations: the multilateral, diplomatic route favored by Europe, and the more muscular, aggressive road favored by the US, particularly under the Bush administration.
Part of the impetus for continuing pressure from the US comes from Congress, where efforts are building to make "regime change" in Iran official US policy.
At the same time, Iranian leaders are under intense domestic pressure to maintain the country's nuclear ambitions and to stand up to international pressures. That was evident yesterday when demonstrators in Tehran burned a British flag and tried to storm the gates of the British Embassy.
Acknowledging the Iranian public's strong identification with the nuclear program, Supreme Leader Ayatollah Ali Khamenei was quoted on state television saying, "Iran will never halt its nuclear activities under any circumstances, and this is our red line."
And in words suggesting the world has not heard the end of Iran's nuclear ambitions, government spokesman Andollah Ramazanzadeh was quoted by Reuters announcing at a weekly press conference: "We are not fully satisfied with the resolution ... but for the time being it was [beneficial] for Iran to accept it."