President Donald Trump in May 2018 announced the US government is withdrawing from the Iran nuclear agreement, which marked one of the biggest foreign policy decisions he's made since entering the White House.
Trump's decision was highly controversial, especially given three of America's top allies – France, Germany and the UK – were strongly opposed to this move.
The president has long described the deal as "terrible," and while the pact has many proponents, he's hardly alone in this view.
The Iran deal — formally known as the Joint Comprehensive Plan of Action (JCPOA) — was one of the crowning diplomatic achievements of former President Barack Obama's tenure, but it has continued to be a divisive issue in Washington since it came to fruition in 2015.
Read more: The oil tanker attacks could make a US-Iran military showdown inevitable, experts warn
Since Trump withdrew from the Iran nuclear deal, tensions between Washington and Tehran have steadily risen and reached a boiling point in recent weeks — roughly a year after the president announced the US was pulling out.
In the year that's passed since Trump's controversial announcement, Iran has remained in compliance with the JCPOA. But the Iranian government on Monday announced it will break from a key component of the JCPOA by ramping up its enrichment of low-grade uranium and increasing its stockpile beyond the limitations outlined in the deal.
To understand the polarizing nature of this deal, why Trump's decision continues to face criticism, and the geopolitical implications of both the US and Iran stepping away from it, here's a quick breakdown of the historic pact and the debate surrounding it.
In July 2015, Iran and six countries reached a historic agreement called the Joint Comprehensive Plan of Action (JCPOA), popularly known as the Iran nuclear deal.
The six major powers involved in these negotiations with Iran were known as the P5+1, which stands for the United Nations security council's five permanent members (the US, France, the UK, China, and Russia) and Germany.
The deal came together after two years of intense discussions and aimed to restrict Iran's ability to develop nuclear weapons in exchange for lifting economic sanctions against Tehran.
Read more: The US is sending a ton of firepower to take on Iran — here's everything headed its way
As part of the deal, Iran agreed to reduce its number of centrifuges — tube-shaped machines that help enrich uranium — by two-thirds. It also agreed to reduce its stockpile of enriched uranium by 98% and limit uranium enrichment to 3.67%.
In other words, Tehran agreed to restrictions that would allow it to have enough enriched uranium to maintain the country's energy needs, without having the ability to build a nuclear bomb.
On top of this, Iran agreed to give access to inspectors from the International Atomic Energy Agency (IAEA), the UN's nuclear watchdog agency, to its nuclear facilities, among other facilities. The IAEA has repeatedly found Iran to be complying with the terms of the pact.
In January 2016, when the IAEA declared Iran was living up to its end of the bargain, all nuclear-related international sanctions against Iran were lifted.
Iran and the US have been enemies for decades. The two countries have an extremely complex history that involved a CIA-orchestrated coup in the 1950s, a pro-American puppet monarch who was overthrown in 1979 via the Islamic revolution, and the infamous hostage crisis at the US embassy in Tehran that followed the uprising.
The constant threats from Iranian leaders against Israel, America's top ally in the Middle East, and chants of "death to America" in Iranian streets have also not helped matters.
In this context, there is a massive distrust for Iran in the US (and vice versa), and Washington has long feared what might happen if the Iranian regime developed a nuclear weapon. Iran made great strides in this regard by the 2010s, hence the Obama administration's efforts to orchestrate the nuclear deal. When the pact was finally settled in 2015, it was widely celebrated as a major diplomatic achievement.
But many (primarily conservative) leaders in Washington still felt the Iran nuclear deal didn't go far enough to limit the country's ability to develop nuclear weapons.
This is because the Iran deal contains sunset clauses, or parts of the agreement that will ultimately expire. Under the deal, the restrictions on Iran's centrifuges go away after 10 years (in 2025) and the limitations on uranium enrichment disappear five years after that (2030). Hence, there are fears that once these restrictions expire, Iran could rapidly develop a nuclear weapon.
"It is clear to me that we cannot prevent an Iranian nuclear bomb under the decaying and rotten structure of the current agreement," Trump said in May 2018. "The Iran deal is defective at its core. If we do nothing we know exactly what will happen."
More broadly, Trump, among others, has argued the deal didn't do enough to address Iran's regional behavior or its missile program. Accordingly, the president wants to negotiate a new deal with Tehran.
Trump's unilateral decision to withdraw the US from the JCPOA was promptly condemned by US allies, who have scrambled to find a diplomatic solution ever since.
Iran has largely remained in compliance with the JCPOA even after Trump withdrew from it, but on Monday announced it will stop complying with a key portion of the deal by the end of the month. This comes amid heightened tensions with the US, which have sparked fears of a military confrontation that could spiral into an all-out war.
Since Trump withdrew the US from the JCPOA, his administration has pummeled Iran with crippling economic sanctions. Iran has accused the US of waging "economic war" and has rejected proposals from Trump to hold talks, perpetuating an impasse that is making the wider world increasingly nervous.
Join the conversation about this story »
NOW WATCH: Meet Blackpink, the K-pop girl group breaking internet music records
