DUBAI — Iranian President Hassan Rouhani warned Wednesday that Iran would increase its enrichment of uranium this weekend to whatever level was needed beyond the cap set by a 2015 nuclear agreement, a move that could further escalate tensions with the United States.

Iran has repeatedly threatened that by July 7 it will increase enrichment above 3.67 percent concentration of Uranium-235 — the level of fissile isotope allowed under the nuclear deal — unless it receives some relief from U.S. sanctions. European countries are struggling to meet Tehran’s demands to keep the 2015 nuclear deal alive. 

“Our enrichment rate is not going to be 3.67 percent anymore,” Rouhani said. “It’s going to be as much as we want it to be.”  

Rouhani’s comments, carried by the state broadcaster, came after Iran on Monday breached the 300-kilogram (660-pound) limit for low-enriched uranium allowed under the deal. 

Amidst high tensions with the U.S., Iran said July 8 it had surpassed the limits on its enriched uranium stockpile. What does that mean for the nuclear deal? (The Washington Post)

That move did not put Iran significantly closer to holding enough high-enriched uranium to produce a nuclear weapon, whereas combining an increase in its uranium stockpile with heightened enrichment levels could reduce its “breakout” time — the period it would need to enable the production of a weapon. 

Uranium enriched to the low level of 3.67 percent U-235 is suitable for fuel in a nuclear reactor, but if it is enriched to much higher levels, around 90 percent, it can be used as fissile material in a nuclear weapon. 

Iran has previously said it plans to raise enrichment to 20 percent — a level that it possessed in its stockpile before the deal and that it argued was needed to produce isotopes for medical and scientific purposes in an old U.S.-supplied research reactor in Tehran. Such a move would mean that Iran could jump to producing weapons-grade uranium more quickly.

Experts estimate that before the nuclear deal, the amount of time that Iran needed to accumulate enough enriched uranium for a nuclear bomb was two or three months. The deal was designed to increase that breakout period to about a year.

Iran argues that it should no longer be bound by the limits of the deal if it does not also benefit from the sanctions relief that the 2015 agreement promised in exchange. Since withdrawing the United States from the deal last year, the Trump administration has reimposed sanctions, which have also made it difficult for European companies to trade with Iran. 

On Wednesday afternoon, President Trump responded on Twitter to Rouhani’s comments: “Iran has just issued a New Warning. Rouhani says that they will Enrich Uranium to ‘any amount we want’ if there is no new Nuclear Deal. Be careful with the threats, Iran. They can come back to bite you like nobody has been bitten before!”

Inspectors from the International Atomic Energy Agency, the United Nations’ nuclear watchdog tasked with verifying whether Iran was sticking to the deal, have said it was compliant until Monday, when Iran announced that it was breaking the stockpile limit.

The unraveling of the 2015 deal comes against the backdrop of increased friction in the Persian Gulf, as analysts say that Tehran is determined to show strength in the face of increasing U.S. sanctions. Trump said he came close to authorizing strikes against Iran late last month after it shot down an American surveillance drone. 

The United States has blamed Tehran for explosions that struck petrochemical tankers in the Gulf of Oman, a charge that Iran denies. Oil infrastructure has also been attacked in Saudi Arabia, and rockets have been fired at U.S. bases in Iraq, where Iran backs numerous Shiite militias.

Rouhani said the United States’ stance on the nuclear deal was contradictory. Trump had repeatedly decried the nuclear deal, officially known as the Joint Comprehensive Plan of Action, or JCPOA, describing it as “bad” and “rotten,” before withdrawing the United States from it last year, but U.S. officials have since denounced Iran for reducing its commitments under it.  

“It’s interesting that until today, the U.S. was referring to the JCPOA as a bad agreement, but now that Iran has decided to distance itself from this ‘bad agreement,’ their shouts and cries are spread all over the world,” Rouhani said. 

With sanctions crippling its economy, Iran took the largely symbolic step of crossing the 300-kilogram threshold Monday. Carrying out its threat of increasing uranium enrichment levels beyond 3.67 percent would be seen as a much more serious breach of the deal and one that could finally kill it by triggering the reimposition of European sanctions. 

Before the nuclear deal, Iran had been building a heavy-water reactor at Arak, which experts deemed a high proliferation risk that could give Iran the capacity to produce weapons-grade plutonium. The nuclear deal required Iran to redesign the plant and pour concrete into the pipes of the reactor’s calandria, or core.

“If you don’t comply with your commitments, the reactor will return to its previous situation,” Rouhani said.  

The nuclear deal “is either good or bad,” Rouhani said.

“If it’s good, everyone should comply with their commitments,” he said. “Comparing your level of commitment to ours, how do you even allow yourselves to object?” 

In an effort to keep Iran in the deal, European countries have tried to set up a trading system that would shield European companies from U.S. sanctions when trading with Iran. But Iran has said this trading system, called Instex, falls short of its expectations, which include being able to sell oil. Washington has threatened to impose sanctions on any country buying Iranian oil.