"Walking away from the JCPOA [Joint Comprehensive Plan of Action] turns our back on America's closest allies and an agreement that our country's leading diplomats, scientists and intelligence professional negotiated," Obama wrote on Twitter Tuesday. "In a democracy, there will always be changes in policies and priorities from one administration to the next. But the consistent flouting of agreements that our country is a party to risks eroding America's credibility and puts us at odds with the world's major powers."
The statement went on to say that that 2015 agreement wasn't "just an agreement between my administration and the Iranian government."
"After years of building an international coalition that could impose crippling sanctions on Iran, we reached the JCPOA together with the United Kingdom, France, Germany, the European Union, Russia, China and Iran. It is a multilateral arms control deal, unanimously endorsed by a United Nations Security Council resolution," the statement concluded.
According to former US Secretary of State John Kerry, the decision "weakens our security, breaks America's word, isolates us from our European allies, puts Israel at greater risk, empowers Iran's hardliners, and reduces our global leverage to address Tehran's misbehavior."
"Instead of building on unprecedented nonproliferation verification measures, this decision risks throwing them away and dragging the world back to the brink we faced a few years ago," he wrote. "The extent of the damage will depend on what Europe can do to hold the nuclear agreement together, and it will depend on Iran's reaction."
The US Treasury said in a statement shortly after Trump's announcement that US sanctions against Iran would go into effect starting in November.
"Washington will not be held hostage to nuclear blackmail," POTUS said, stressing that his decision would lead to a "much safer" America.
Following Trump's announcement, Iranian President Hassan Rouhani stated that the US was committing "psychological warfare" and that the decision continued the US' long history of undermining international treaties.