The next episode in the long-running international attempt to curb Iran’s drive for nuclear-weapons capacity comes next week, when representatives of the so-called P5+1 nations (the five permanent members of the U.N. Security Council: the United States, Russia, China, Great Britain and France, plus Germany) meet with Iranian officials in Moscow. Two previous meetings, one in Istanbul and the other in Baghdad, accomplished little, as the Iranians bobbed and weaved, prevaricated and stalled while their nuclear program proceeded apace, as yet undeterred by increasingly punishing economic sanctions imposed to stop them

Optimists believe the Moscow talks may turn out better since Tehran faces the prospect of a European Union embargo on Iranian oil, to go fully into effect July 1. But Iran’s announcement — on the virtual eve of the Moscow meetings — that it will construct a nuclear-powered submarine hardly suggests a regime ready to back down. Indeed, it is further confirmation of what the International Atomic Energy Agency noted in its November report are the distinct military dimensions of Iran’s nuclear project.

Both at the Moscow meetings and afterward, leaders who understand the danger a nuclear Iran poses to the stability of the Middle East and the world should devise policy on the basis of five key principles:

•  First, while everyone hopes that negotiations will succeed in deterring Iran from proceeding with its nuclear plans, talks must be conducted with great care. Negotiation must not become an end in itself, and thus the excuse for delay after delay. The Iranians are past masters at this, raising extraneous issues, creating distractions and blaming the other side for everything. Furthermore, compromising on a deal that leaves Tehran in sight of nuclear-weapons capacity is worse than no deal at all, since it creates the illusion of a resolution to the problem.

In 2010, the P5+1 insisted that Iran stop all enrichment of uranium, but in Moscow they will reportedly ask only for an end to 20 percent enrichment, allowing anything less. Since as little as 3.5 percent enrichment is already 70 percent of the way to a nuclear weapon, even should the Iranians concede to the current P5+1 proposal nothing would be solved.

• It is easy enough to warn Iran that in regard to its nuclear ambitions, all options are on the table, including the use of force should diplomacy fail. But to be effective, the threat must be credible. Tehran must be made to understand that there truly is an iron fist underneath the velvet glove.

• Sanctions on Iran must be ratcheted up and the existing ones enforced. The Iranian economy has been hit hard — Iranian officials have admitted as much — and further sanctions could well bring about a rethinking in Tehran. In the United States, beside sanctions enacted at the federal level, nine states have passed legislation barring all dealings with Iran; the other states should follow suit.

Evaders of international sanctions who continue to trade with Iran, whether they are governments, companies or individuals, should be named and shamed for giving aid and comfort to a regime that threatens world peace and security.

• Whatever considerations motivated the recent publicity about our stealth warfare against the Iranian nuclear program, the danger the latter poses to the world surely justifies initiatives aimed at crippling the computer systems controlling Tehran’s project. Whoever is behind this ingenious computer warfare should continue the work, and even more sophisticated strategies developed.

• Iran deserves political and diplomatic isolation so long as it maintains its quest for a nuclear capacity. That means not only cutting off diplomatic relations — which many nations have done — but also refusing to appear together with Iranian officials, shake their hands, or give any indication that Tehran is a respected member of the community of nations.

For example, Iranian President Ahmadinejad is coming to Brazil for a UN-sponsored conference that begins June 20. Brazil’s president and other top officials can make an important statement about Iran’s pariah status by refraining from meeting with or even greeting him.

These five points make for an ambitious agenda, but one that is surely justified by the grave threat Iran poses.

Brian D. Siegal is director the American Jewish Committee’s (AJC) Miami and Broward County Office.