If you're confused about whether a nuclear deal with Iran would be good for America - or for Israel - join the club. The club, that is, of folks who are debating the benefits of a deal versus the costs.

For unyielding critics of any deal, especially in Congress, such analysis is irrelevant. Their minds are made up - as negotiations with Iran wind toward a March 31 target date for a framework accord on curbing its nuclear program. They are convinced, as is Prime Minister Benjamin Netanyahu, that Iran is an existential threat to Israel and that no deal can be good. Or they are ready to damn any deal President Obama would endorse.

But for the rest of us, such a debate is essential. Even those who support a deal in principle, myself included, have deep qualms. And Obama's weak Mideast policy raises questions about how hard a bargain he'll drive.

So how can an ordinary citizen evaluate a draft accord that may (or may not) be reached soon? Let me suggest four rules to help you make up your mind.

Rule One: The risks of a deal must be weighed against the steep costs of no deal. (Keep this rule in mind when evaluating the terms of any deal.)

If negotiations collapse, Iran will resume its program of nuclear enrichment, which has essentially been frozen under an interim accord. Sanctions forced Iran to the table, but they did not prevent Tehran from building more centrifuges in the past. Nor will they stop it from resuming work if talks end.

Moreover, if talks collapse, the international sanctions regime is likely to crack sooner rather than later, especially if the United States is blamed. At that point, there will be growing pressure from Israel and Gulf Arab states for a U.S. attack on Iran's nuclear sites. This might set the nuclear program back a couple of years, but it won't destroy it, because Iran already has the scientific know-how. A U.S. or Israeli strike would likely convince the ayatollahs to oust international inspectors and sprint toward bomb production - something they've refrained from doing until now.

A new Mideast war would also have unpredictable and dangerous consequences for the region - as did the Iraq war. This explains why many top Israeli security experts, including former heads of Mossad (the Israeli CIA), have reacted sharply to Netanyahu's hostility toward talks.

"Netanyahu wants to stop Iran at any cost, which means a military operation is almost inevitable," said former Israeli Brig. Gen. Shlomo Brom at a conference held by the liberal Zionist organization J Street. "We know how to start wars but not how to end them," he continued. "So we must consider the cost. That doesn't exclude military action, but only as a last resort."

Rule Two: There is no perfect deal. The debatable question is how to define an acceptable deal.

Netanyahu would like Iran's nuclear-energy program to be completely dismantled, but this is a non-starter. Instead, the goal is to curb the program sufficiently so that, should Iran try to "break out" or "sneak out," it would take at least a year, during which time its violations would become known.

That, in turn, requires highly intrusive verification measures that Iran can't circumvent.

International monitors must be given access to any site they suspect might harbor illegitimate activity. They must be able to conduct snap inspections. Iran must answer questions about past activity on suspect nuclear-weapons programs - which it has failed to do despite promises made two years ago.

Critics decry the fact that a deal would have a 10- to 15-year sunset clause and would require a gradual lifting of sanctions. Those worries are legitimate, but there are ways to assuage them. Some possibilities: Iran could be required to submit to intrusive sanctions even after the accord ends. And there could be a "snapback" clause in any deal that automatically reinstates sanctions if Iran is found to violate its terms.

Rule Three: Don't expect a deal to make Iran behave better in the region. But recognize that a failed deal won't improve Tehran's behavior either.

Shiite Iran's star is rising because so many Sunni Arab governments have collapsed due to corruption and popular revolts - or Western intervention. Obama's incoherent policy toward Syria and Iraq helped Iran gain strength in the region as American influence waned.

So, yes, it is possible that Iran will become more aggressive if it gets sanctions relief. But air strikes on Iran would make the ayatollahs more aggressive still. Better to think of how to strengthen Sunni allies in the region and coordinate the rollback of ISIS.

Rule Four: If Iran won't ink a framework deal this month, keep talking. (The final deadline for negotiations isn't until July.) The Iranian public wants sanctions relief, which puts pressure on the ayatollahs to stay at the table. This gives Washington and its European allies leverage to hang tough for a better deal - if Congress doesn't pile on more sanctions next month, with the goal of blowing up negotiations. Better to recognize Rule One - that the costs of failure will be heavy - and work toward fashioning an acceptable deal.