Well, well, well. Remember when Israel agreed to US terms to avoid nuclear sites while retaliating for Iran's massive ballistic missile attack? It turns out that the Iranians' attempts to play cute with the IAEA gave Israel an opening to destroy a key research facility -- and leave the Iranians unable to complain about it.

When the Iranians first began pursuing nuclear weapons, much of that work took place at a facility in Parchin. After their program got exposed, the Iranians shuttered Parchin and moved that work into more defensible locations. The Iranians have insisted ever since that Parchin no longer played an active role in nuclear research, but that turned out to be a lie, Axios reports. And both the US and Israel knew it:

• Israeli and U.S. intelligence began detecting research activity at Parchin earlier this year, including Iranian scientists conducting computer modeling, metallurgy and explosive research that could be used for nuclear weapons.

Flashback: Last June, the White House officials privately warned the Iranians in direct conversations about the suspicious research activities, Axios reported.

• The U.S. hoped the warning would make the Iranians stop their nuclear activity, but they continued, the officials said.

The concern over the Taleghan 2 facility at Parchin hit levels so high in US intelligence that they stopped reporting that they had no evidence of Iranian nuclear-weapons development. So when it came time to craft the response to the October 1 missile attacks, the Israelis had a golden opportunity to end that threat, or at least severely curtail it, without violating the agreement with the US. In any other administration, this would have had the blessing of the US, and perhaps it did:

• President Biden asked Israeli Prime Minister Benjamin Netanyahu not to attack the Iranian nuclear facilities in order not to trigger a war with Iran, U.S. officials said.
• But Taleghan 2 was not part of Iran's declared nuclear program so the Iranians wouldn't be able to acknowledge the significance of the attack without admitting they violated the nuclear non-proliferation treaty.

Now the Iranians can't complain about this target, not unless it wants to admit to pursuing nuclear weapons. The realization of this loss could explain why the Iranians went from shrugging off the Israeli retaliation to threats of a counter-retaliation strike almost immediately. Iran still insists that it will counter-retaliate at some point, in fact, although the outcome of the election in the US might have them thinking twice about it. 

There's another reason for second thoughts, though:

• "The strike was a not so subtle message that the Israelis have significant insight into the Iranian system even when it comes to things that were kept top secret and known to a very small group of people in the Iranian government," a U.S. official said.

That might have the Iranians thinking veeeerrrrrry carefully about escalation, too. Not only will the incoming US administration be much less likely to hold Israel back on target selection, they have to wonder what other targets Israel has in mind. They have already sussed out the activity at Parchin, which can't have been too big of a surprise after the American warning about it earlier in the year. The Israelis also penetrated the IRGC's security in successfully assassinating Ismail Haniyeh in Tehran this summer. Without American pressure to avoid truly escalatory blows, Israel might just start hitting places where Iranian leadership hides out, as well as IRGC command and control functions. 

At least this answers questions that arose after the retaliatory attack, when some of us scratched our heads over targeting selection. The real threats to Israel in Iran are the nuclear weapons and the leadership, so it didn't make sense to leave both untouched with this opportunity. The Iranians know the Israelis did attack and damage the former, and now have to decide whether to provoke Israeli into seriously attacking the latter.