A satellite image shows significant damage to buildings at Iran's Kermanshah Missile Facility after repeated Israeli Strikes on the site.

When Israel launched its series of strikes against Iran last week, it also issued a number of dire warnings about the country’s nuclear program, suggesting Iran was fast approaching a point of no return in its quest to obtain nuclear weapons and that the strikes were necessary to preempt that outcome.

But US intelligence assessments had reached a different conclusion – not only was Iran not actively pursuing a nuclear weapon, it was also up to three years away from being able to produce and deliver one to a target of its choosing, according to four people familiar with the assessment.

Another senior US official told CNN that Iran is “about as close as you can get before building (a nuclear weapon). If Iran wanted one, they have all the things they need.”

Now, after days of Israeli airstrikes, US intelligence officials believe that so far, Israel may have set back Iran’s nuclear program by only a matter of months, according to one of those people, a US official. Even as Israel has done significant damage to Iran’s facility at Natanz, which houses centrifuges necessary to enrich uranium, a second, heavily fortified enrichment site at Fordow has remained effectively untouched.

Israel lacks the capability to damage Fordow without specific US weapons and aerial support, defense experts say.

“Israel can hover over those nuclear facilities, render them inoperable, but if you really want to dismantle them it’s either a US military strike or a deal,” said Brett McGurk, a former top diplomat to the Middle East under the Trump and Biden administrations and a CNN analyst.

That raises a key dilemma for the Trump administration, which is struggling to avoid becoming entangled in a costly, complex war in the Middle East.

Although President Donald Trump has made clear that he does not want to involve the US in Israel’s efforts to destroy Iran’s nuclear infrastructure, the administration recognizes that the only way Israel can knock out Iran’s nuclear program is with American military assistance, sources told CNN over the weekend – in particular, US bombs capable of damaging underground facilities and the B-2 bombers that carry them.

It’s a tightrope that has led to debate among the more isolationist members of the president’s advisers and some of Trump’s more hawkish Republican allies – as well as some hedging from the president.

“We’re not involved in it. It’s possible we could get involved. But we are not at this moment involved,” Trump told ABC News on Sunday morning.

Trump, speaking from the G7 Summit in Canada on Monday, urged Israel and Iran to begin talks “before it’s too late.”

US Central Command, responsible for American military operations in the Middle East, has conveyed a greater sense of urgency than the civilian intelligence community when it comes to Iran’s pursuit of a nuclear weapon.

In the lead-up to Israel’s latest attack, Central Command had endorsed a more dire timeline, believing Iran could obtain a usable nuclear weapon more quickly if it were to sprint towards that goal, according to a source familiar with the discussions.

In recent weeks, some US military leaders, including US Central Command chief Gen. Michael Kurilla, have requested more resources to defend and support Israel as it continues to trade fire with Iran – although not to help it launch offensive attacks.

“{Kurilla} would want to be prepared for the most challenging contingency,” according to a source familiar with the matter, referring to his push for positioning US assets in the Middle East in support of Israel.

The US is realigning forces in the region as the conflict escalates to ensure American forces are protected and help defend Israel if necessary.

On Monday, a US official told CNN that the USS Nimitz Carrier Strike Group is moving to the Middle East “without delay.”

Some US naval assets capable of defending against ballistic missiles already in the Middle East are expected to move into the eastern Mediterranean “in the coming days,” the official added. Two US Navy ships intercepted missiles in defense of Israel at least twice over the weekend, the official said.

Same intelligence, different conclusions

US military and intelligence officials have long said that the US and Israel often differ on how to interpret information on Iran’s nuclear program, although they closely share it.

Trump’s Director of National Intelligence, Tulsi Gabbard, testified in March that the US intelligence community, “continues to assess Iran is not building a nuclear weapon and Supreme Leader Khamenei has not authorized a nuclear weapons program that he suspended in 2003.”

Trump, asked where he personally stands on how close Iran was to getting a nuclear weapon, given what Gabbard testified just months ago, told reporters on Air Force One early Tuesday, “very close.”

When pressed on her specific testimony that they weren’t, Trump said, “I don’t care what she said. I think they were very close to having it.”

Gabbard insisted Tuesday there was no daylight between Trump’s assessment and her own prior characterization that Iran was not building a nuclear weapon.

“President Trump was saying the same thing that I said in my annual threat assessment back in March,” Gabbard told reporters as she arrived on Capitol Hill Tuesday for an appearance before the Senate Appropriations Committee.

Israeli Prime Minister Benjamin Netanyahu was pressed Sunday during an interview with Fox News on why Israel’s intelligence differed from Gabbard’s congressional testimony.

Asked if something changed between the end of March and this week and if the US intel was wrong, Netanyahu said: “The intel we got and we shared with the United States was absolutely clear, was absolutely clear that they were working, in a secret plan to weaponize the uranium. They were marching very quickly.”

The International Atomic Energy Agency, a top international watchdog, said last week that Iran had amassed enough uranium enriched at levels just below weapons-grade to potentially make nine nuclear bombs, which it termed “a matter of serious concern.”

The challenge, for Iran, is producing not merely a crude nuclear weapon – which experts say Iran could potentially do within the space of months if it decided to – but also producing a working delivery system, which could take much longer.

As US intelligence officials – and the IAEA – work to assess the damage Israel has caused to Iran’s nuclear architecture, there is some concern that the blitz might cause Iran to do what US officials believe it hasn’t up until now: pursue weaponization.

But, said one source familiar with the latest intelligence, “Iran is reeling. Not sure they have the capacity or expertise to do that anymore.”

Iran’s fortified enrichment facility

Israel has yet to seriously damage perhaps the most impenetrable fortress of Iran’s nuclear program: Fordow, an enrichment facility buried deep beneath a mountain.

“It comes back to one question: Fordow, Fordow, Fordow,” McGurk told CNN’s Wolf Blitzer on Monday.

“That is something the United States can take out. That is something the Israelis will have a lot of difficulty doing. If this ends with Fordow intact, you could actually have a worse problem,” said McGurk. “You could actually have Iran more inclined to go to a nuclear weapon and they have that infrastructure intact.”

Trump and his administration have made the case that a diplomatic solution could still come to fruition. But Iran has told Qatar and Oman that it will not engage while it is under attack from Israel, a regional diplomat told CNN, and Israel has signaled no short-term end to the operation.