French President Emmanuel Macron vowed on Wednesday that Iran will never possess any nuclear weapons, a day after he announced his readiness to work with the United States on a new nuclear deal. Speaking at Congress at the end of his three-day US trip, he said: “Iran shall never possess any nuclear weapon. Not now not in five years, not in 10 years, never.” He said the 2015 nuclear deal with Iran, which US President Donald Trump has harshly criticized, was not perfect but must remain in place until a replacement is forged. “It is true to say that this agreement may not address all concerns and very important concerns,” Macron told lawmakers in English. “But we should not abandon it without having something more substantial instead. That’s my position.” “This policy should not lead us to war in the Middle East. We must ensure that stability is reached in the region,” he continued. Later, he told reporters at the conclusion of his US trip that he had no "inside information" on whether Trump will pull the US out of the Iran deal, but that it is clear he "is not very much eager to defend it." Trump on Tuesday called the deal "ridiculous," but did not say whether he would withdraw the US by the May 12 deadline he has set. Macron pointed out that withdrawing from the deal is "a campaign commitment that (Trump) took a long time ago." Commenting on Syria, the French president hailed before Congress the air strike carried out by the US, Britain and France against regime chemical facilities. “They acted to destroy chemical weapons and protect the credibility of the international community,” he stressed, while vowing to cooperate to reach a solution to the humanitarian crisis in Syria and reach a political end to the conflict. He said that he discussed this issue with Trump, adding that the political solution serves the expectations of the Syrian people in the post-ISIS phase. The Western strike on April 14 was a response to the regime’s chemical weapons attack against the town of Douma that killed at least 40 people a week earlier. A day after Macron had put on a show of warmth and brotherly affection for Trump at the White House, his blunt Congress speech prizing engagement over isolationism reinforced his emerging role as a top defender of the liberal world order. "We can choose isolationism, withdrawal and nationalism. This is an option. It can be tempting to us as a temporary remedy to our fears," Macron said. "But closing the door to the world will not stop the evolution of the world. It will not douse but inflame the fears of our citizens." Issuing a bleak warning, he urged against letting "the rampaging work of extreme nationalism shake a world full of hopes for greater prosperity." On climate change, he implicitly lamented Trump’s moves to withdraw from the global emissions pact reached in Paris. Macron said humans are "killing our planet" and added: "Let us face it: There is no Planet B." "On this issue, it may happen we have disagreements between the United States and France. It may happen, like in all families," he stated. "But thats for me a short-term disagreement." Asked by French reporters about his comments later during a visit to the Martin Luther King Jr. Memorial, Macron said with a smile that he does not expect Trump to rejoin the Paris accord, but does expect that America will.