LONDON: Iran increased its threat to regional security on Tuesday by boasting that its nuclear program was more advanced than ever.

Ali Akbar Salehi, head of the Atomic Energy Organization and vice president to Hassan Rouhani, said that if US President Donald Trump succeeded in dismantling the 2015 deal to curb the program, Tehran would resume uranium enrichment with more sophisticated equipment.

“If we have to go back and withdraw from the nuclear deal, we certainly do not go back to where we were before,” he said. “We will be standing on a much, much higher position.”

Iran stores centrifuges to enrich uranium at its underground Natanz facility, under surveillance by the UN nuclear watchdog, the International Atomic Energy Agency. Salehi said it would build a new facility at Natanz that will produce more advanced centrifuges.

“This does not mean we are going to produce these centrifuges now,” he said. “This is just a preparation. If Iran decides to start mass production of such centrifuges, we would be ready for that.”

If the nuclear deal fell apart, Iran would react in stages, Salehi said. It could enrich uranium “to 20 percent, because this is our need,” and could also increase its stockpile of enriched uranium.

Iran’s fragile economy is already suffering from US withdrawal from the nuclear deal and the reimposition of economic sanctions. Prices have soared, the rial has plunged in value and thousands of Iranians have taken part in street protests demanding regime change. Further sanctions in November will target Iran’s energy sector and slash its crucial oil revenues.

Tehran hoped that the other signatories to the nuclear deal — Russia, China, France, Germany and the UK — would keep it alive, but faced with the threat of blocked access to the US financial system, Western companies from aircraft manufacturers to oil firms have pulled out of Iran.

In a further blow to Iran’s economy, the US renewed its warning to civilian airlines on Tuesday to avoid Iranian airspace. Hundreds of international flights pass over Iran every day, and each is required to pay an overflight fee. Iran refuses to disclose its revenue from these fees, but it is thought to be considerable.

The US Federal Aviation Administration said flying over Iran was risky because of the possibility of interception, and military activities related to the war in Syria.

Flight Service Bureau, which advises airlines, said the deteriorating relationship between the US and Iran must be taken into account when planning flights in Iran’s airspace.

“Although the reopening of Iraqi airspace in November last year has provided additional routing options ... there is no perfect route in the region, and operators must consider their preference for Iraq vs Iran,” it said.