Leaders of Russia, France, Germany as well as the Chinese premier have reiterated their support for the 2015 nuclear deal as Donald Trump has exited the U.S. from the internationally backed agreement.

China, Russia, Germany, and France are among the signatories of the nuclear deal with Iran.

Talking to reporters in St Petersburg on Thursday, Russian President Vladimir Putin and his French counterpart Emmanuel Macron questioned Trump’s withdrawal from the international agreement, officially called the Joint Comprehensive Plan of Action and backed by the UN Security Council.

“I was personally assured that Iran is fulfilling all its obligations, so the question arises what grounds there were to exit this agreement,” Putin said, Telegraph reported.

“We welcome the efforts of Iran and Europe to preserve this deal, while understanding that it will be hard,” he added.

“Russia has never approved unilateral actions,” he said, referring to the renewed U.S. sanctions against Iran.

He noted, “Any action against a sovereign government can be taken only by United Nations Security Council, all the rest are illegitimate.”

Trump pulled the U.S. out of the JCPOA on May 8 and vowed to reimpose sanctions against Iran.

Since Trump’s withdrawal, Iran has been seeking guarantees that its economic interests are protected otherwise it will resume nuclear activities at a greater speed.

Putin also warned of “lamentable consequences” if the nuclear deal was not preserved.

Speaking at a joint news briefing at Beijing’s Great Hall of the People, German Chancellor Angela Merkel and Chinese Premier Li Keqiang also defended the nuclear deal on Thursday, The Nation reported.

Li warned that abandoning the deal with Tehran “will not just impact Iran, but also have a negative impact on (the ability) to solve other hot international issues through peaceful negotiations”.

The German leader also sounded the alarm about the economic impact of the move on Europe.

Merkel said that if European companies pull out or shrink operations in Iran to avoid falling foul of U.S. law, it would “create an opportunity for businesses in other countries to step in and play a greater role”.

The backing for the nuclear agreement by Merkel came hours after Leader of the Islamic Revolution Ayatollah Khamenei issued a set of demands from Europe to save the nuclear deal. He warned that Iran would restart its nuclear activities if they failed to act swiftly.

Ayatollah Khamenei said the JCPOA could only continue if the Europeans fulfill these conditions including: Promising not to ask Iran about its ballistic missile program or its regional activities; guaranteeing that Iran’s oil will continue to be sold; and having European banks guarantee financial transactions with Iran.