There’s just one Iranian nuclear facility left on Israel’s hit list — and it may be up to the US to take it out.

Iran’s Fordow fuel enrichment plant is a fortress built deep within the mountains — up to 300 feet underground.

That’s out of reach of Israel’s known munitions. Only America’s 15-ton “bunker buster” bomb, the GBU-57A/B Massive Ordnance Penetrator, is thought to be capable of touching it.

While Israel has surprised Western intelligence in the past with the scope of its arms and strategies, nothing the Jewish state has shown so far suggests it has the means to penetrate Fordow’s defenses, said Nicholas Carl, a research manager at the American Enterprise Institute’s Critical Threats Project.

“America is the only partner who can step in and do that,” Carl told The Post.

So far, President Trump has suggested that he’s much more interested in playing peacemaker than wading into the conflict on Israel’s side.

Completed in 2009, Fordow lies hidden in the mountains about 100 miles south of Tehran as one of three major nuclear enrichment sites in Iran.

Iran has spent years fortifying the facility, which has been able to avoid most major attacks from Israel that target Tehran’s nuclear program.

“Tehran has made sure the facility can survive airstrike attacks, making Fordow a much harder target than the other facilities that have been hit through the years,” Carl explained.

While the base does not necessarily house the most advanced nuclear enrichment plants in Iran, it does have highly advanced centrifuges that are a prime target for Israel.

“The entire operation … really has to be completed with the elimination of Fordow,” Yechiel Leiter, the Israeli ambassador to the US, told reporters Friday during the first wave of attacks.

To reach those centrifuges, Israel would need America’s so-called “bunker busters,” bombs specifically designed to penetrate deep below ground to blow up their target.

The “MOP” and other American bunker busters are several times more powerful than the 1-ton American-made bombs that the Israeli air force reportedly used to burrow underneath Beirut to kill Hezbollah chief Hassan Nasrallah last year.

It remains unclear if Israel has more powerful penetrating bombs than that on hand.

But while Washington has the capability, the White House may not have the same initiative to lend its firepower for a direct strike against Iran.

“The US, without a doubt, has a strategic interest to prevent Iran from acquiring nuclear weapons … but if we do get involved, we need to be cognizant of the risks involved,” Carl said. “The US needs to calculate the outcome from this type of attack on Iran.”

While Iran still has other nuclear enrichment bases scattered across the country, with another even more heavily fortified lab reportedly under construction, many analysts believe that the fall of Fordow would be necessary to fulfill Israel’s ambition of ending Tehran’s nuclear ambition once and for all.

“If you don’t get Fordow, you haven’t eliminated their ability to produce weapons-grade material,” Brett McGurk, who has served as Middle East coordinator for several American presidents, told the New York Times.