DUBAI, United Arab Emirates -- Israel, Saudi Arabia and Iran's other rivals have long wanted to scuttle the nuclear deal, which they see as undermining the strategy they say the world should be taking: a tough, confrontational stance against Tehran's ambitions in the region.

But the deal's unravelling could backfire and spark even more unrest in the Middle East. Also, if Iran follows with an all-out revival of its nuclear program, Saudi Arabia has threatened to launch a nuclear weapons program of its own in response.

Traditional foes Saudi Arabia and Israel -- both U.S. allies -- have found common ground as critics of the 2015 deal, which was brokered by Iran and the five permanent members of the U.N. Security Council, Germany and the European Union.

U.S. President Donald Trump's decision Tuesday to withdraw from the accord doesn't mean the deal's immediate collapse -- the Europeans still back it, and much depends on how Iran reacts. But it does deeply weaken the agreement and could open the way for the U.S.'s regional allies to take a more aggressive approach on Iran.

The leaders of France, Germany and Britain said Trump's decision to leave the accord is a threat to global efforts to prevent the spread of nuclear weapons, but Saudi Arabia and Israeli Prime Minister Benjamin Netanyahu welcomed the move.

Netanyahu actively sought to scuttle the deal from the start, even when it was still being brokered. He has bluntly said the world would be better off without any deal than with what he calls the "fatally flawed" agreement reached during the Obama administration.

He has pushed for confrontation against Iran as the Shiite-led nation builds up its military presence in neighbouring Syria in support of President Bashar Assad. Netanyahu warns Iran will use its troops and weaponry there to threaten Israel.

"We are determined to block Iran's aggression against us even if this means a struggle. Better now than later," he said this week at a Cabinet meeting.

Israel is suspected of being behind strikes on Iranian bases in Syria in recent weeks that killed a number of Iranian and Syrian troops. Leaders in Iran have been cautious not to retaliate against Israeli provocations at a time when the nuclear deal still has backing from other major world powers.

That could change if the deal breaks down. Israeli security officials say the military already has gone on heightened alert this week, fearing an Iranian reprisal.

Yoel Guzansky, a senior researcher at Israel's Institute for National Security Studies, believes the current deal has "many, many problems," but says there are consequences to walking away from it, including the possibility of escalating violence and instability in the region.

"Not just in Syria but also in the Gulf and elsewhere. It could mean a more volatile Middle East, absolutely," he said.

Supporters of the deal say it places strict limits on Iran's nuclear facilities that make it unable to produce a bomb during the lifetime of the deal. UN inspectors have repeatedly confirmed that Iran is abiding by the accord's terms.

Critics of the deal object to a sunset provision that would allow Iran to resume enriching uranium at high levels in 15 years, unless an extension or longer-term deal is negotiated. Europe could join the U.S. in re-imposing sanctions in retaliation if it does so.

Opponents also point to issues that are not addressed in the deal, such as Iran's ballistic missile program, its support for militias in the region and its expanding influence. The deal's architects say those issues can be negotiated separately and should not be allowed to wreck an accord that halted progress toward a bomb.

Saudi Arabia is also more aggressively confronting Iran on multiple fronts under the directives of King Salman's son and heir, Crown Prince Mohammed bin Salman, who has consolidated power in the kingdom.

Prince Mohammed said in a recent CBS interview that if Iran develops a nuclear bomb, the kingdom would "without a doubt" follow suit as soon as possible. Israel is widely believed to have a nuclear arsenal of its own, though it has never publicly acknowledged it.

The Sunni-ruled kingdom, which is fighting Shiite rebels known as Houthis in Yemen, accuses Iran of supplying the Houthis with ballistic missiles that have targeted the kingdom, including the capital, Riyadh. Likewise, Israeli airstrikes in Syria are believed to have targeted shipments of Iranian missiles bound for Lebanon's Hezbollah group.

Columnists in state-linked Saudi media outlets have grown increasingly hawkish as pressure mounts on Iran.

Saudi journalist Mashari Althaydi wrote in a column published on the Al-Arabiya news website that Iran's possession of nuclear weapons would make it necessary for Saudi Arabia to possess similar weapons for deterrence.

Mohammed Al-Shaikh, a Saudi writer, called for stirring up "everything that would domestically distract" Iran from harming Saudi security and stability.

Despite strong reservations about the deal, Saudi Arabia tepidly supported it in public when it was first reached, seemingly as a gesture to President Barack Obama. Still, Obama's rapprochement with Iran cooled ties between Riyadh and Washington.

The kingdom has since wholeheartedly embraced Trump and his tough talk.

Thomas Lippman, an expert on Saudi Arabia and Middle Eastern affairs, said he fails to see how the kingdom benefits from the deal collapsing.

"The Saudis really need to be careful. Iran has three times Saudi Arabia's population, and it has battle-tested armed forces and it has an ally in the Houthis in Yemen," he said.

"As far as I can tell, there is in fact a struggle for the future of Iran going on among Iranians ... Let that struggle play itself out," Lippman added.

Israel, meanwhile, continues to try and build international pressure against Iran.

"Israel for many years now has been preparing for many scenarios vis-a-vis Iran... Israel is not sitting quietly not doing anything," said Guzansky, the Israeli researcher, who is a former Iran analyst on the prime minister's National Security Council.

Although Israel has never acknowledged it, its Mossad spy agency is widely believed to be behind the assassinations of at least five Iranian nuclear scientists in the years preceding the 2015 negotiations. Last week, Netanyahu showed off what he said were tens of thousands of secret documents about the Iranian nuclear program stolen by the Mossad. Many believe Netanyahu showed off the trove of information in part to send a message to Iran about his intelligence agency's capabilities.

Associated Press writer Ian Deitch in Jerusalem contributed to this report