Iran has enough highly enriched uranium to build "several" nuclear weapons if it chooses, the United Nations’ top nuclear official is now warning. But diplomatic efforts aimed at again limiting its atomic program seem more unlikely than ever before as Tehran arms Russia in its war on Ukraine and as unrest shakes the Islamic Republic.

While offering a caveat on Tuesday that "we need to be extremely careful" in describing Iran’s program, Rafael Mariaono Grossi of the International Atomic Energy Agency bluntly acknowledged just how large Tehran’s high-enriched uranium stockpile had grown.

"One thing is true: They have amassed enough nuclear material for several nuclear weapons, not one at this point," Grossi said.

Gross assured a European Parliament subcommittee in Brussels on Wednesday that Iran has not yet built a nuclear weapon and the West should redouble efforts to stop them from doing so. 

Even at the height of previous tensions between the West and Iran, before the 2015 nuclear deal, Iran never enriched uranium as high as it does now.

For months, nonproliferation experts have suggested Iran had enough uranium enriched up to 60% to build at least one nuclear weapon — though Tehran long has insisted its program is for peaceful purposes. Uranium enriched to more than 90% can be weaponized. Iran has 70 kilograms (154 pounds) of uranium enriched to 60% purity and 1,000 kilograms to 20% purity, Grossi shared.

The Argentine diplomat then referred to Benjamin Netanyahu’s famous 2012 speech to the United Nations, where the Isaeli prime minister exhorted the United Nations General Assembly to draw "a clear red line" to stop Iran from developing nuclear weapons.

In a theatrical gesture, Netanyahu held up a cartoon-like drawing of a spherical bomb and drew a red line below the fuse, "before Iran completes the second stage of nuclear enrichment to make a bomb," he said.

"It’s not a question of whether Iran will get the bomb. The question is at what stage can we stop Iran from getting the bomb," Netanyahu said.

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Analysts point to what happened with North Korea, which had reached a 1994 deal with the U.S. to abandon its nuclear weapons program. The deal fell apart in 2002. By 2005 and wary of U.S. intentions after its invasion of Iraq, Pyongyang announced it had built nuclear weapons. Today, North Korea has ballistic missiles designed to carry nuclear warheads that are capable of reaching the U.S.

Iranian diplomats for years have pointed to Supreme Leader Ayatollah Ali Khamenei’s preachings as a binding fatwa, or religious edict, that Iran wouldn’t seek an atomic bomb. However, Iranian officials in recent months have begun openly talking about the prospect of building nuclear weapons.

Talks between Iran and the West ended in August with a "final text" of a roadmap on restoring the 2015 deal that Iran until today hasn’t accepted.

As Iran’s rial currency plunges further to historic lows against the dollar amid its crises, Iranian officials including Foreign Minister Hossein Amirabdollahian also have made unsupported claims about American officials agreeing to their demands or frozen money abroad being released.

At the U.S. State Department, the denials about Iran’s claims have grown more and more pointed.

"We’ve heard a number of statements from the Iranian foreign minister that are dubious if not outright lies, so I would just keep that broader context in mind when you point to statements from the Iranian foreign minister," State Department spokesperson Ned Price said Monday in a response to a question.

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In Dec. 2022, State Department spokesperson Ned Price said that the Iran nuclear deal is "not our focus right now," noting the administration was instead focusing on supporting citizens protesting the death of Mahsa Amini, a young woman detained in September by the country’s morality police.

"Iran’s demands are unrealistic. They go well beyond the scope of the JCPOA," Price said, using the acronym for the deal, the Joint Comprehensive Plan of Action.

Critics say the Biden administration’s statements over this month show its unfailing allegiance to JCPOA that, according to one U.S. think tank study, would funnel $275 billion in benefits to Tehran in its first year and $1 trillion by 2030. 

A spokesman for Senator Cruz, R-Texas, told Fox News Digital that "Sen. Cruz believes that the Biden administration is ideologically obsessed with reentering a nuclear deal with Iran, and that they are doing everything possible to keep that possibility open. He believes that they prioritize the deal above other critical interests they claim they have, including supporting the women-led protests against the Iranian regime and helping our Ukrainian allies take out the Russian and Iranian forces using drones to devastate Ukrainian military and civilian targets."

Price and others in Biden’s administration say any future talks with Iran remain off the table as Tehran cracks down on the months-long Amini protests. At least 527 people have been killed and over 19,500 arrested amid the unrest, according to Human Rights Activists in Iran, a group monitoring the protests.

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Another part of the Americans’ exasperation — and increasingly of the Europeans as well — comes from Iran arming Russia with the bomb-carrying drones that repeatedly have targeted power plants and civilian targets across Ukraine. It remains unclear what Tehran, which has a strained history with Moscow, expects to get for supplying Russia with arms. One Iranian lawmaker has suggested the Islamic Republic could get Sukhoi Su-35 fighter jets to replace its aging fleeting composed primarily of pre-1979 American warplanes, though such a deal hasn’t been confirmed.

Such fighter jets would provide a key air defense for Iran, particularly as its nuclear sites could increasingly be eyed. Israel, which has carried out strikes to halt nuclear programs in Iraq and Syria, has warned it will not allow Iran to obtain a nuclear bomb.

The U.S. and Israel also launched their largest-ever joint air, land and sea exercise this week with6,400 US troops participating, more than 1,500 Israeli troop, using over 140 aircraft, 12 naval vessels, High Mobility Artillery Rocket Systems and multiple-launch rocket systems, in an operation dubbed Juniper Oak 23.2.

Officials at the Pentagon said the operation enhances Washington's ability to respond to contingencies and "underscores the US commitment to the Middle East region".

The Pentagon described the drill as "not meant to be oriented around any single adversary or threat." However, it comes amid the heightened tensions with Iran and includes aerial refueling, targeting and suppressing enemy air defenses — capabilities that would be crucial in conducting airstrikes.

For now, Grossi said there was "almost no diplomatic activity" over trying to restore the Iran nuclear deal, an agreement he now describes as "an empty shell." But he still urged more diplomacy as Tehran still would need to design and test any possible nuclear weapon.

"We shouldn’t give up," he said.

Fox News' Benjamin Weinthal and the Associated Press contributed to this report.