UNITED NATIONS (Reuters) - France made a new plea on Monday for the United States to preserve the 2015 Iran nuclear deal and suggested its provisions expiring after a decade could be strengthened, as U.S. President Donald Trump again criticized the agreement as “deeply flawed.”

The pact between Tehran and six world powers, which calls for Iran to curb its nuclear program in return for relief from economic sanctions, is under threat as Trump must decide by Oct. 15 whether to certify Iran is keeping its end of the bargain.

If Trump, who as recently as Thursday accused Iran of violating “the spirit” of the deal, chooses not to certify, the pact could unravel, possibly triggering a regional arms race.

The Republican president, who has called the agreement struck under his Democratic predecessor, Barack Obama, “the worst deal ever negotiated,” made no secret of his views during a meeting with French President Emmanuel Macron.

“The president believes that the JCPOA is deeply flawed, and he did share his views with President Macron about how he believes the deal is flawed,” Brian Hook, director of policy planning at the U.S. State Department, told reporters. The pact is formally called the Joint Comprehensive Plan of Action.

“The president was very candid with him about what he thinks are the shortcomings. ... He told him that it is under review and that they are taking a hard look at the Oct. 15th decision and more broadly how to fix the Iran deal,” Hook said.

Hook said the two also discussed an integrated strategy against Iran that would take into account what he described as Iran’s support for terrorism, its ballistic missile program, its destabilization in the Middle East and other aggressions.

Asked if he planned to stick with the pact, Trump earlier told reporters as he began a meeting with Israeli Prime Minister Benjamin Netanyahu on Monday: “You’ll be seeing very soon.”Israeli officials have said changes Israel wants in the JCPOA include lengthening the 10-year freeze on Iran’s nuclear development program or even making that suspension permanent and destroying centrifuges rather than just halting their operation.

The deal was negotiated with Iran by the United States, Russia, China, Britain, Germany and France. The six will meet with Iran at the ministerial level on Wednesday.

The prospect of Washington reneging on the agreement has worried some of the U.S. allies that helped negotiate it, especially as the world grapples with another nuclear crisis, North Korea’s nuclear and ballistic missile development.

“It is essential to maintain it to avoid proliferation. In this period when we see the risks with North Korea, we must maintain this line,” French Foreign Minister Jean-Yves Le Drian told reporters.

“France will try to convince President Trump of the pertinence of this choice (keeping the accord), even if work can be done to complement the accord after 2025,” he said.

A senior French official said Trump had not given Macron an indication on whether he had made up his mind during their Monday bilateral.

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However, the official said Macron had put on the table the prospect of new nuclear negotiations after 2025 during his bilateral with Iranian President Hasan Rouhani and warned him that Tehran should stop provoking the United States with its regional activities.

“We feel the post 2025 subject is a red line, but our president put it on the table because it’s a concern and a legitimate request that we must make,” the official said. “2025 will arrive quickly and we have to be ready before Jan 1. 2025, so he asked that we think together how to work on this question.”

If Trump does not certify that Iran is complying with the agreement, the U.S. Congress will have 60 days to decide whether to reimpose sanctions waived under the deal.

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Iran Supreme Leader Ayatollah Ali Khamenei warned on Sunday that Tehran would react strongly to any “wrong move” by Washington on the nuclear deal.

DIVIDING WORLD POWERS

Paris took one of the hardest lines against Tehran in the negotiations, but has been quick to restore trade ties and Macron has said repeatedly there is no alternative to the deal.

French officials say Iran is respecting the JCPOA and that, were the International Atomic Energy Agency (IAEA) to say otherwise, a mechanism exists to reimpose sanctions.

The IAEA is the body ensuring the accord is carried out, but the United States and Iran quarreled over how Tehran’s nuclear activities should be policed at an IAEA meeting on Monday after a U.S. call last month for wider inspections.

U.S. Secretary of State Rex Tillerson argued on Friday that Washington must consider the full threat it says Iran poses to the Middle East when crafting its new policy toward Tehran.

A senior French diplomat underlined that the nuclear deal was achieved in large part because it was not linked to all the other grievances the United States may have had with Iran.

With Europeans not on the same page as the Trump administration, Iranian officials say they have an opportunity to divide the P5+1 group that negotiated the deal with Iran.

A senior Iranian diplomat and a former nuclear negotiator said he believed the Europeans had no intention of following Trump’s overtly aggressive Iran policy.

“They are wise. Look at the region. Crisis everywhere. From Iraq to Lebanon. Iran is a reliable regional partner for Europe, not only a trade partner but a political one as well,” the diplomat said.

“European powers have been committed to the deal. The IAEA has repeatedly confirmed Iran’s commitment to the deal. Trump’s insistence on his hostile policy towards Iran will further deepen the gap among the P5+1 countries,” the diplomat said.