This article is more than 2 years old

This article is more than 2 years old

Theresa May has used a pair of speeches at the UN summit in New York to firmly contradict Donald Trump’s isolationist view of the world, arguing that the best way to resist extremist forces was through close cooperation between countries.

The prime minister, speaking a day after Trump’s address to the UN general assembly explicitly rejected global cooperation in favour of a “doctrine of patriotism”, even delivered a polite if direct rebuke to the US president over his abandonment of the Iran nuclear deal.

May, who was addressing a special session of the UN security council on weapons proliferation chaired by Trump, told the president that the deal remained “the best means of preventing Iran developing a nuclear weapon”.

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The prime minister, in her main address to the general assembly shortly afterwards, reiterated her call for transnational cooperation, saying public disillusionment about economic and political systems risked a return to influence for far left and far right ideologies.

“We have to show there is a better way to meet the concerns of our people,” she said. “That way lies in global cooperation between strong and accountable states based on open economies and inclusive societies.”

While Downing Street was adamant that May’s choice of words was not intended to be critical of Trump, whom she was meeting one-to-one in a final engagement before leaving New York on Wednesday evening, the strong language would be seen by many as a counterpoint to Trump’s stark statement to the UN: “We reject the ideology of globalism and we embrace the doctrine of patriotism.”

She did also say countries should address the worries of “those who feel that the global economy is not working for them”, citing reform of the World Trade Organization as one area where action was needed.

In her security council speech May also warned of potential renewed military action if chemical weapons were again used in Syria.

Russia and other backers of Syria’s government should seek to avoid repeated use of chemical weapons, she said, adding: “For there must be no doubt: we will respond swiftly and appropriately if they are.”

May also condemned what she said was Russia’s “desperate fabrication” in response to the Salisbury nerve agent attack.

On Iran, May said the long-negotiated international deal on the country’s nuclear programme, officially known as the Joint Comprehensive Plan of Action (JCPOA), had been “an important step forward” in addressing worries about Tehran’s nuclear ambitions.

She said: “It remains the best means of preventing Iran developing a nuclear weapon, and we are committed to preserving the JCPOA as long as Iran continues to abide by its obligations in full.”

Trump announced in May he was breaking with European allies over the Iran deal, and signed an executive order reimposing sanctions on any foreign company that continued to do business with Iran. May has repeatedly and publicly disagreed with Trump over his decision.

She praised Trump for his talks with the North Korean leader, Kim Jong-un, saying this had “created a historic opportunity for complete, verifiable and irreversible denuclearisation” on the Korean peninsula.

But here, too, she played up the role of international cooperation, saying previous sanctions imposed by the UN “played no small part” in getting Kim to the negotiating table.

May, in her condemnation of Russia over the novichok attack in Salisbury, said: “We have taken appropriate action, with our allies, and we will continue to take the necessary steps to ensure our collective security. Russia has only sought to obfuscate through desperate fabrication.”

More widely, May praised the multilateral treaties on weapons proliferation as “one of the greatest achievements of the international community, demonstrating the value of global cooperation”.

She said: “It has improved all of our security. It has brought a measure of predictability and stability. And it has paved the way to arms control agreements and disarmament.”

May ended by again reminding Trump about the benefits of cross-national work: “Mr President, it was collective engagement by states across the globe that produced the counter-proliferation framework.

“Even the most powerful recognised that investing in collective rules-based restraint was the only effective way of addressing national security interests and avoiding unilateral recourse to force.”

Despite her criticism of Trump’s strategy, the prime minister later held talks with him in New York, where they discussed the issue of a US-UK trade deal following Brexit.

Facebook Twitter Pinterest The UK prime minister, Theresa May, with the US president, Donald Trump, in New York. Photograph: Peter Foley/AFP/Getty Images

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“They agreed that Brexit provides a wonderful opportunity to strike a big and ambitious UK-US free trade agreement,” a No 10 statement said. They also discussed Syria, and taking action against what Downing Street called “Iran’s destabilising regional activity”.

The White House statement on the talks cited discussions on various international situations, but made no mention of a trade deal.

May, asked by reporters ahead of the talks how the British people could believe Trump would stick to his word over trade, given his habit of sometimes changing his mind about international agreements and his tendency to routinely say things that are untrue, argued he had shown trustworthiness.

She cited examples including the US’s decision to expel Russian diplomats in the wake of the novichok nerve agent attack on Salisbury.

This meant he could be trusted on a trade deal, May said, arguing the omens were positive: “It’s in both our interests to do that good trade deal, and I believe that when we have negotiated that deal it will indeed be put in place.”