Iranian state television has confirmed that the country has ended its implementation of the Additional Protocol, which allows for so-called snap inspections of nuclear-related sites, signaling the further disintegration of atomic safeguards in place since a 2015 nuclear deal with world powers.
The move on February 22 came after Tehran floated the possibility of dramatically escalating uranium enrichment as Washington and its Western partners scrambled to salvage the so-called Joint Comprehensive Plan Of Action (JCPOA) that the previous U.S. administration abandoned in 2018.
Word of the imminent breakout from the Additional Protocol followed defiant statements by Iranian Supreme Leader Ayatollah Ali Khamenei that included a vow to "not back down on the nuclear issue."
Khamenei also suggested that Tehran could boost uranium enrichment as high as 60 percent -- below the 90-percent level for a bomb.
But it is well above the 20-percent enrichment announced by Tehran last month and many multiples above the 3.67-percent limit agreed as part of the JCPOA.
A U.S. State Department spokesman was later quoted as saying that 60-percent enrichment sounded "like a threat" but that Washington would not respond to hypotheticals and posturing.
Earlier, White House press secretary Jenn Psaki said that the United States' European allies were still awaiting a response from Iran on an offer to host an informal meeting of current members of the JCPOA.
Newly inaugurated U.S. President Joe Biden's administration vowed on February 22 that it will return to "strict compliance" with the JCPOA if Tehran does the same.
U.S. Secretary of State Antony Blinken told a UN-sponsored Conference on Disarmament in Geneva in a pre-recorded speech that Washington hopes to extend and bolster the nuclear deal that has come under intense pressure lately.
"Working with allies and partners, we will also seek to lengthen and strengthen the JCPOA and address other areas of concern, including Iran's destabilizing regional behavior and ballistic-missile development and proliferation."
At the same conference, German Foreign Minister Heiko Maas called on Iran to fully comply with the pact and said compliance was in Tehran's interest.
"It is in Iran's best interest to change course now, before the agreement is damaged beyond repair," Maas said.
Maas said that Germany expected "full compliance, full transparency and full cooperation" from Iran with the International Atomic Energy Agency (IAEA), whose chief Rafael Grossi reached a temporary agreement in Iran on February 21 on site inspections that he called a "significant achievement."
That deal effectively bought time with inspections continuing as all sides try to salvage the agreement, which was pushed to the brink of collapse when U.S. President Donald Trump withdrew nearly three years ago and reimposed tough sanctions.
The United States and other governments have accused Iran of secretly trying to build a nuclear weapons capability, a charge that Tehran has consistently rejected despite years of what the IAEA said was obfuscation and deception.
Khamenei, who has the final say on political and religious affairs in Iran, said on February 22 that "we will act to the point that is needed and the country requires" and that "we could bring enrichment to 60 percent" for a number of purposes.
"The Islamic Republic will not back down on the nuclear issue and will strongly continue down the path of what the country requires for today and tomorrow," the AFP news agency quoted him as saying.
A day earlier Press TV quoted Khamenei as saying that Iran will never move toward the development of nuclear weapons.
The so-called Additional Protocol allows IAEA inspectors to visit undeclared sites in Iran at short notice.
Tehran is demanding that Washington remove punishing sanctions Trump reimposed in 2018, while Washington has called on Iran to first return to all of its nuclear commitments.
"Iran must comply with its safeguards agreements with the IAEA and its international obligations," Blinken said on February 22.
"The United States remains committed to ensuring that Iran never acquires a nuclear weapon," the top U.S. diplomat said. "Diplomacy is the best path to achieve that goal."
Meanwhile the commander of U.S. forces in the Middle East, General Kenneth McKenzie, was quoted as warning Tehran against any provocation.
"I would think this would be a good time for everybody to behave soberly and cautiously, and see what happens," McKenzie said during a visit to Oman, according to AFP. "I do believe we will be prepared for any eventuality, however."
In the standoff, Iran's conservative-dominated parliament has demanded that the country limit some inspections by the IAEA from February 23.
Grossi hammered out a temporary technical deal with Tehran during his visit, whereby Iran will continue to allow access to UN inspectors to its nuclear sites -- but will for three months bar inspections of other, non-nuclear sites.
Grossi said afterwards that the "temporary solution" enables the IAEA to retain "a necessary degree of monitoring and verification work."
Iran's Foreign Ministry spokesman, Saeed Khatibzadeh, said on February 22 that the talks had "resulted in a very significant diplomatic achievement and a very significant technical achievement."
Khatibzadeh stressed that the outcome was "within the framework of parliament's binding law."
Under the agreement reached over the weekend with the IAEA, Iran will temporarily suspend so-called "voluntary transparency measures" -- notably inspections of non-nuclear sites, including military sites suspected of nuclear-related activity.
Tehran will for "three months record and keep the information of some activities and monitoring equipment" at such sites, Iran's Atomic Energy Organization said.
This means that cameras will keep running at those sites, "but no footage will be given to the IAEA," Khatibzadeh said.
The footage will be deleted after three months if the U.S. sanctions are not lifted, Iran's atomic body has said.