I’m pretty pessimistic about the possibility of rolling back the Iranian nuclear program. The more interesting challenge, it seems, is constraining the growth of the program in any meaningful way. That leads me to focus on one of Gary’s last questions first: Should we be prepared to accept arrangements that allow Iran to maintain a limited enrichment program under enhanced international monitoring?
Of course, so long as Iran wants to preserve a real nuclear option, we’re going to be in a bind: if some particular arrangement for Iranian enrichment satisfies us, it is unlikely to be acceptable to Tehran, and vice versa. Setting that aside for the moment, though, the simplest answer to the question is probably yes – and something Gary writes suggests why:
Assuming sufficient low enriched UF6, for example, a unit of 3,000 P-1 centrifuge machines is likely to take at least a few months to produce enough HEU for a single bomb, during which time the facility would be vulnerable to military attack.
If the Iranian program remained at its present size, any overt breakout would provide the world with enough warning time to knock out its enrichment facility. Military action in that context would attract far more international support than a preventive strike aimed at a facility producing LEU would.
There are, of course, other dangers involved in leaving even the present enrichment infrastructure in place. Legitimate nuclear activity could provide cover for efforts in support of a covert track. And while the United States might gain comfort from knowing that it could preempt an Iranian breakout, some of Iran’s neighbors might disagree; the result could be a regional arms race even in the absence of an Iranian bomb. Yet these problems would exist even if Iran scaled back its program, and the alternative – completely eliminating the Iranian program – seems entirely impractical.
The other question is whether we could tolerate a somewhat larger nuclear program than what Iran has today. I suspect the answer is yes, so long as we were confident that any shift from LEU to HEU production would be detected early enough to facilitate a military strike – and depending on the inspection arrangements, that might be possible with a substantial Iranian facility. It would be best, however, to avoid this sort of outcome.