US President Donald Trump's announcement on Tuesday that he intends to withdraw the United States from the Iran nuclear deal drew opposing reactions from world leaders.

While some praised the president for turning his back on a "flawed" deal, others argued that Trump's decision itself undermines the Joint Comprehensive Plan of Action (JCPOA), concluded in 2015 after years of negotiation, and raises uncertainty not only between the US and Iran but also between trans-Atlantic allies.

Read more:  What is the Iran nuclear deal?

Germany

Foreign Minister Heiko Maas said that Germany, France and the UK would speak with one voice on the Iran accord: "We remain committed to the nuclear deal," he said in Berlin on Wednesday. "The deal is working. We want to keep the controls and transparency rules in place," he added.

Maas also called on Iran to act calmly and fulfill the obligations laid out in the deal.  

The German minister said that Trump's decision was "incomprehensible" and had dealt a blow to stability in the Middle East. He also addressed the fears of a fallout for German businesses, promising that the potential effects on companies would be analyzed. 

Read more: Iran nuclear deal: Germany's special role and plans

In the aftermath of Trump's announcement, German business leaders had expressed concern over potential US-imposed sanctions on German companies that have relations with Iran: "The reintroduction of US sanctions would cause enormous insecurity in the German economy," said Volker Treier, the head of foreign economics at the Association of German Chambers of Commerce and Industry.

Europe

French President Emmanuel Macron, who had tried to persuade Trump to remain in the deal, told DW in an interview that Trump's decision was a "mistake."

"I regret the decision of the American president," Macron told DW. "I think it's a mistake and that's why we Europeans have decided to remain in the nuclear agreement of 2015."

The French Foreign Ministry announced Wednesday that representatives from France, Germany, and the UK — all signatory nations of the nuclear deal — would meet with Iranian representatives next Monday.

Read more: Iran nuclear deal: Has Europe done enough to save it?

Federica Mogherini, the European Union's foreign policy chief, who helps supervise the way Iran and the six world powers implement the deal and settle any disputes, said in a press statement on Tuesday that the deal "is not in the hands of a single country."

"The European Union is determined to act in accordance with its security interests and to protect its economic investments," she said. In a message directed at Iran, Mogherini said: "Do not let anyone dismantle this agreement. It is one of the biggest achievements diplomacy has ever delivered, and we have built this together."

'Show restraint'

In a joint statement provided by British Prime Minister Theresa May's office, Germany, France and the UK requested the US not obstruct other nations as they attempt to implement the deal and urged Iran to "show restraint" and continue fulfilling its own obligations.

UK Foreign Minister Boris Johnson told parliament on Wednesday that Britain had done its best to prevent Trump from leaving the deal. He added that the UK would stick to the deal as long as Iran continues to fulfill its terms. The minister added that Britain would never accept a nuclear-armed Iran.

Russia, which also helped negotiate the Iran deal, said it was "deeply disappointed" by Trump's unilateral decision.

Iran

On his official website, Iran's Ayatollah Ali Khamenei, who is Iran's highest religious and state authority, derided Trump's announcement as "silly and superficial."

Iranian President Hassan Rouhani told French President Emmanuel Macron that European signatories have a "limited opportunity" to save the deal's future.

Read more: Can Angela Merkel and Emmanuel Macron save the Iran nuclear deal?

"Under the current conditions, Europe has a very limited opportunity to preserve the nuclear deal, and must, as quickly as possible, clarify its position and specify and announce its intentions with regard to its obligations," Rouhani said, according to Iran's semi-official ISNA.

But Rouhani has threatened to restart Iran's nuclear program, saying "whenever it is needed, [Iran] will start enriching uranium more than before."

Middle East

Israeli Prime Minister Benjamin Netanyahu hailed Trump's "historic move," calling the deal a "recipe for disaster, a disaster for our region, a disaster for the peace of the world."

Read more: Israel divided over Donald Trump's withdrawal from Iran nuclear deal

Israel is a close ally of the United States and Netanyahu has been in favor of scrapping the deal. Saudi Arabia and the United Arab Emirates, two other US allies, also praised Trump's announcement.

"Iran used economic gains from the lifting of sanctions to continue its activities to destabilise the region, particularly by developing ballistic missiles and supporting terrorist groups in the region," the Saudi Foreign Ministry said in a statement.

Anwar Gargash, UAE Minister of State for Foreign Affairs, tweeted that the accord "would have led to a regional nuclear race with little trust in Iran's intentions."

US politicians divided

In a rare move, former US President Barack Obama, whose administration negotiated the current deal, called Trump's decision "misguided" in a statement posted on his Facebook page.

"The reality is clear. The JCPOA is working — that is a view shared by our European allies, independent experts, and the current US Secretary of Defense. The JCPOA is in America's interest — it has significantly rolled back Iran's nuclear program," Obama said.

"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."

American congressional leaders were split over Trump's decision to take the US out of the deal.

Senate majority leader, Republican Mitch McConnell, said the Iran deal was a "deeply flawed agreement" and that he shared Trump's commitment that "Iran should never be able to acquire or develop a nuclear weapon."

Conversely, Senate minority leader, Democrat Chuck Schumer, said it appeared the Trump administration had no plan going forward.

Read more: Opinion: Trump's Iran nuclear deal exit dangerous for the world

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cmb, dv/rt (AP, Reuters)