US President Donald Trump announced on Tuesday that the United States will reimpose sanctions on Iran and abandon the 2015 international accord to curb Iran's nuclear program.

Trump's decision will not only ramp up tensions with Iran, but could also further unsettle Washington's ties with its European allies — particularly France, Germany and the UK — who sought to convince the US leader to remain in the deal.

Earlier, US media reported on the president's decision to pull out of the deal.

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

What Trump said:

• Announcing his decision at the White House, Trump lambasted the deal, calling it "defective at its core."
• "We cannot prevent an Iranian nuclear bomb under the decaying and rotting structure of the current agreement," he said.
• "The United States will no longer make empty threats," he added towards to the end of his address.
• Trump said the US "will be instituting the highest level of economic sanctions" against Iran as well as new economic penalties. 
• He did not specify how long of a grace period the administration will grant for businesses and governments to untangle their operations in Iran to avoid US penalties.

Iran to remain in nuclear deal

Iranian President Hassan Rouhani said that despite Trump's decision, Tehran would remain in the international accord. Iranian officials are due to discuss the US announcement with Europe, Russia and China.

"If we achieve the deal's goals in cooperation with other members of the deal, it will remain in place ... By exiting the deal, America has officially undermined its commitment to an international treaty," Rouhani said in a televised speech.

He also described the US move as "psychological warfare."

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

How world leaders reacted

French President Emmanuel Macron tweeted shortly after Trump's announcement that "France, Germany and the UK regret the US decision" to leave the deal. He said that the remaining parties will work on addressing Iran's "ballistic activity" as well as ensuring stability in the Middle East in "Syria, Yemen and Iraq."

Germany, the UK and France reaffirmed their commitment to the deal and urged for the US not to obstruct other countries as they attempt to implement the deal, according to a joint statement provided by British Prime Minister Theresa May's office. May, Macron and German Chancellor Anglea Merkel spoke by telephone shortly before Trump's speech.

The European Union's top diplomat, Federica Mogherini, called on the international community to stick with the deal, saying that the EU is "determined to preserve it." She noted that she was "particularly worried" by Trump's announcement of new sanctions against Iran.

Read more: Donald Trump withdraws US from Iran nuclear deal: How the world reacted

In a rare move, former US President Barack Obama — whose administration brokered the deal — criticized his successor's decision to leave the deal. He said Trump's move was a "serious mistake" and emphasized that independent experts, US officials and EU allies agree the deal is working.

Richard Grenell, the new US Ambassador to Germany, sent out a warning to German businesses on Twitter, saying that "German companies doing business in Iran should wind down operations immediately."

Israeli Prime Minister Benjamin Netanyahu, who advocated for scrapping the accord with Iran, praised Trump's decision. Netanyahu said the deal was a "recipe for disaster, a disaster for our region, a disaster for the peace of the world."

Saudi Arabia, a longtime US ally and rival of Iran's, said: "The kingdom supports and welcomes the steps announced by the US president towards withdrawing from the nuclear deal... and reinstating economic sanctions against Iran."

What is the Iran nuclear deal? In July 2015, international powers and Iran agreed to a deal that called for lifting crippling international sanctions in exchange for Iran dismantling its nuclear program. Known as the Joint Comprehensive Plan of Action (JCPOA), the deal with Iran was signed by the United States, Germany, the United Kingdom, China, Russia, France and the European Union.

Read more: A closer look at the Iran nuclear deal 

Why does Trump object to the deal? The US leader has criticized the deal for not addressing Iran's ballistic missile program, or Tehran's support of Syrian President Bashar Assad. He's also been critical of the deal's expiration dates, including a provision that lifts restrictions on Iran's uranium stockpile and enrichment after 15 years.

Where does Europe stand? German, French and British leaders as well as EU leaders in Brussels all back the dealall back the deal and tried to persuade the US president to remain. They've warned that an exit from the deal would undo years of work that has kept nuclear weapons out of Iran.

What happens next: European nations will now need to work with Iran in order to hold the agreement together. A US exit will likely hit Iran's economy hard, with the country's currency already at record lows in recent weeks ahead of Trump's announcement.

rs/kms (AP, AFP, Reuters)