With the incumbent president and his main challenger deeply at odds over a 2015 nuclear deal and other aspects of policy toward Tehran, the outcome of the U.S. election on November 3 could play a powerful role in shaping Iran's development for years to come.
President Donald Trump, who is seeking reelection on the Republican Party ticket, wants to maintain sweeping economic sanctions on Iran in an effort to force it to renegotiate the international agreement, which he asserts is badly flawed and threatens U.S. security.
Democratic Party nominee Joe Biden, who worked on the nuclear deal as vice president under President Barack Obama, contends that Trump's policy of "maximum pressure" on Iran has "badly backfired," provoking Tehran's leadership and undermining stability.
The long-negotiated agreement between major global powers and Tehran, the Joint Comprehensive Plan Of Action (JCPOA), is intended to make it harder for Iran to potentially develop atomic weapons by restricting its nuclear activities in exchange for sanctions relief.
Trump withdrew the United States from the deal in 2018 and reinstated sanctions, subsequently beefing them up. Since then, Iran's economy has been hit hard, with the value of its currency sharply declining, and Washington and Tehran have come close to military conflict on two occasions.
Iran fired missiles at a U.S. base in neighboring Iraq in January 2020 in retaliation for Washington's killing of Major General Qasem Soleimani, a senior commander who led the elite Quds Force, sparking fears of war.
Months earlier, in June 2019, Trump said he called off a military strike at the last minute that would have targeted three sites inside Iran in retaliation for the downing of a U.S. drone by Tehran, citing concerns that many people would be killed.
Biden has said he is prepared to pursue a more diplomatic course with Iran and -- if Iran returns to compliance with its obligations -- have the United States rejoin the JCPOA, whose conclusion was seen by supporters as perhaps the signature foreign-policy achievement of the Obama administration.
"There is a smart way to counter [Tehran] -- and a self-defeating way. Trump's approach is demonstrably the latter," Biden said in January 2020 as U.S.-Iranian tensions escalated.
Trump has laid the blame for the current tensions in the long-sour relationship at the feet of the Obama administration, an indirect swipe at Biden, charging that it agreed to a nuclear deal that benefits Tehran at the expense of U.S. security interests.
The nuclear agreement is hanging by a thread, with Washington's European allies seeking to preserve it. A second Trump term would likely spell its demise, analysts say, but a Biden victory might not be enough to resolve the problems required to keep it alive.
Biden and Trump are expected to spar over Iran policy on September 26, when they face off in the first of three debates scheduled to be held before the election.
'Worst Deal Ever'
Trump's policies toward Iran seem unlikely to have come as a surprise to Tehran.
During his 2016 campaign for the presidency, Trump promised to pull the United States out of the JCPOA. It was negotiated by the five permament UN Security Council members -- the United States, Russia, China, Britain, and France -- plus Germany and the European Union.
As part of the deal, Iran agreed to cap its uranium enrichment and stockpile for 15 years and allow international observers to verify its compliance, including access to undeclared sites. In return the United States and other powers agreed to ease sanctions, unfreezing up to $150 billion of Iranian funds held in banks around the world.
Trump lashed out at the agreement, calling it "the worst deal ever." He said Iran would use the money coming in as a result of sanctions relief to finance its terrorist activity throughout the Middle East.
Iran's activities abroad include deploying military advisers and fighters to Syria to back President Bashar al-Assad's government in the devastating war there, selling advanced weapons to Yemen's Huthi rebels as part of their fight against the Saudi-backed government, financing the militant group Hizballah in Lebanon, and stirring up protests against the United States in Iraq.
The Trump administration has also assailed the JCPOA for incorporating "sunset provisions" that allow restrictions to expire, saying that opens the door to Iran eventually acquiring nuclear weapons, as well for not addressing Iran's ballistic-missile program.
"The JCPOA enriched the Iranian regime and enabled its malign behavior, while at best delaying its ability to pursue nuclear weapons and allowing it to preserve nuclear research and development," the White House said in a May 8, 2018, statement announcing the withdrawal -- a move aimed at forcing Tehran to negotiate a new deal that would address Trump’s concerns.
But Iran has taken no steps to seek a new or altered agreement, and soon announced it would step up work on its enrichment program, in violation of the JCPOA.
It didn't take long for tensions to escalate.
Fears Of War
When several oil tankers were attacked in the Gulf of Oman in May and June of 2019, the United States pinned blame on Iran. Days after the June tanker attack, a U.S. drone was shot down by Iranian forces, nearly prompting Trump to strike at several targets in Iran, an escalation that could have prompted a tough response by Tehran.
Tensions flared up again in December as the United States carried out strikes against Iranian-backed militias following their attack on an Iraqi base.
Iranian-backed protesters stormed the U.S. Embassy compound in Iraq days later, and the United States killed Soleimani in a drone strike near Baghdad's airport on January 3. The killing made waves in the global community and Iran retaliated by firing missiles at a U.S. base in Iraq, provoking fears of a regional war.
Since the first tanker attacks in the Gulf of Oman, the United States had increased the number of troops in the Middle East by about 18,000 to counter Iran.
Trump asserted that Soleimani had planned to carry out attacks on U.S. diplomats and military personnel and said his killing was intended to "stop a war."
Biden suggested it was nearly the opposite. "When the Iran deal was in force, we did not have this dangerous cycle of tit-for-tat provocation and response," he said on January 7, following the Iranian missile attack against the U.S. base.
"A president who says he wants to end endless war in the Middle East is bringing us dangerously close to starting a new one," Biden said.
The Trump administration continues to impose new sanctions on Iran, including measures against another 11 entities and three individuals on September 3, in hopes that the "maximum pressure" policy will force the government’s resistance to a new deal to crack.
Critics charge that this may be pushing Iran into the arms of another U.S. adversary, China.
Tehran and Beijing have reportedly agreed to a 25-year, $400 billion deal on energy, infrastructure, and defense that could help Iran lessen the impact of the sanctions.
The Trump administration is now trying to block any arms sales to Iran indefinitely -- and in doing so, some observers say, essentially the JCPOA. As part of the nuclear deal, a UN embargo on arms sales to and by Iran is set to expire in October, a step the Trump administration vehemently opposes.
In late August, the administration filed a complaint with the UN Security Council in a bid to reimpose all UN sanctions on Iran, including the arms embargo, on the grounds that Tehran was not in compliance with the JCPOA.
The Iranian government has increase enrichment and uranium stockpiles in response to the U.S. sanctions. U.S. Secretary of State Mike Pompeo said on September 8 that the stockpile was more than 10 times the limit set by the JCPOA.
The European states that are parties to the JCPOA "must wake up to the reality that the nuclear deal is history and should join us in imposing strong sanctions," Pompeo said in a tweet.
The UN Security Council has 30 days to pass a resolution waiving the UN sanctions, but it is almost certain to fail as the United States has veto power.
Facing both U.S. and UN sanctions, Iran may decide to exit the JCPOA, some experts say.
Biden has said he would rejoin the JCPOA and build on it if Iran also moved back into compliance with its obligations. "The only way out of this crisis is through diplomacy -- clear-eyed, hard-nosed diplomacy grounded in strategy, that's not about one-off decisions or one-upmanship," he said in January.
However, analysts say that the JCPOA could be dead before the election as a result of the U.S. pressure, and that any new deal could -- like the existing one -- take years to cobble together.
Even if the JCPOA is still intact, a Biden administration could face difficulties getting Iran back into compliance, said Behnam Ben Taleblu, senior fellow at the Foundation for Defense of Democracies, a Washington-based think tank.
If Tehran doesn't feel it needs economic relief from sanctions as much as Biden needs a diplomatic achievement, it could hold out for more concessions from the U.S. president, putting his administration in a tough position.
"What would [a Biden administration] do? Revert to the Trump pressure policy? It remains a big question," Taleblu told CNBC in August.
Michael Singh, a managing director at the Washington Institute and former senior director at the National Security Council, said the JCPOA was "effectively dead," regardless of the outcome of the election.
Trump won't return to the agreement should he win, while Biden may face demands from Iran for compensation should he try to preserve the deal, Singh said.
"The U.S. won't make unilateral concessions, so the likely outcome is either a stalemate or an effective renegotiation of the deal," he said in a September 2 tweet.