The United States and its partners will work to "lengthen and strengthen" the 2015 nuclear deal with Iran, Secretary of State Antony Blinken pledged at a UN-backed disarmament conference in Geneva on Monday.

At the same time, President Joe Biden's administration will address "Iran's destabilizing regional behavior and ballistic missile development and proliferation," Blinken said.

"The United States remains committed to ensuring that Iran never acquires a nuclear weapon. Diplomacy is the best path to achieve that goal," Blinken said.

Biden has stated that if Iran comes back into "strict compliance" with the 2015 pact, then his administration would do the same, Blinken said.

Iran threatens further uranium enrichment

Meanwhile, Iran’s Supreme leader Ayatollah Ali Khamenei said on Monday that the Islamic republic might enrich uranium up to 60% purity if needed.

"Iran's uranium enrichment level will not be limited to 20%. We will increase it to whatever level the country needs ... We may increase it to 60%," the state television quoted Khamenei as saying.

The boost would mean that Iran would surpass the 3.67% limit that it had accepted under the 2015 nuclear deal but it would still be below the 90% mark required to make an atomic bomb.

Khamenei added that Iran will not yield to pressure on its nuclear activity.

US State Department spokesman Ned Price called Khamenei's comments “a threat" and declined to respond to what he deemed "hypotheticals" and "posturing."

Efforts to revive deal

Former President Donald Trump pulled the United States out of the deal in 2018, while pursuing a policy of "maximum pressure." After taking office in January, Biden has sought to resume diplomacy and rescue the 2015 deal.

In recent years, however, Iran has slowly walked away from many of the agreement's limitations. Crucially, it has begun enriching its uranium up to 20%, creeping very close to weapons-grade levels.

Tehran wants Washington to take the first step by scrapping the sanctions that Trump reimposed on it in 2018.

Iran curbs inspectors' access

Following emergency meetings over the weekend, both the UN and Iran agreed to a "technical understanding" to continue "necessary" monitoring for up to three more months.

At the same time, however, Tehran would go ahead with its plan to slash cooperation with the agency on Tuesday. This includes offering "less access'' to UN weapons inspectors.

The nation will temporarily suspend so-called voluntary transparency measures — notably inspections of nonnuclear sites, including military sites suspected of nuclear-related activity.

Tehran will also deny the International Atomic Energy Agency (IAEA) real-time access to footage from surveillance cameras installed at some sites. If sanctions are not lifted within three months, officials will delete it, Iran's Atomic Energy Organization has said.

With the new agreement, Director General Rafael Grossi said the IAEA would be able to "retain the necessary degree of monitoring and verification work."

The last-minute deal had prevented the IAEA from "flying blind," he said, adding that now "political discussions at other levels can take place."

Zarif warns of new troubles unless sanctions are lifted 

Moscow welcomed the temporary agreement on Monday, with Foreign Ministry spokeswoman Maria Zakharova saying the Kremlin hoped it would help "the overall political situation."  

Iran's Foreign Ministry on Monday also hailed the outcome as a "very significant diplomatic achievement."

Foreign Minister Mohammad Javad Zarif had warned Sunday that if the economic sanctions were not lifted, his nation would continue scaling back its commitments under the 2015 nuclear deal.

The stockpile of "enriched uranium will increase," he said, stressing that Tehran had the right within the agreement to stop observing commitments "totally or partially" if the other parties fail to honor theirs.

"We are still in the partial phase," Zarif said. "We can be total."

mb/dj (AFP, AP, Reuters)