Joe Biden has announced an end to US support for Saudi-led offensive operations in Yemen, as part of a broad reshaping of American foreign policy.

In his first foreign policy speech as president, Biden signaled that the US would no longer be an unquestioning ally to the Gulf monarchies, announced a more than eightfold increase in the number of refugees the country would accept, and declared that the days of a US president “rolling over” for Vladimir Putin were over.

“America is back,” Biden declared in remarks delivered at the state department, capping a whiplash fortnight of dramatic foreign policy changes since his 20 January inauguration. “Diplomacy is back at the center of our foreign policy.”

Biden said the conflict in Yemen, which has killed more than 100,000 Yemenis and displaced 8 million, had “created a humanitarian and strategic catastrophe”.

“This war has to end,” Biden. “And to underscore our commitment, we’re ending all American support for offensive operations in the war in Yemen, including relevant arm sales.”

However, he said the US would continue to provide defensive support to Saudi Arabia against missile and drone attacks from Iranian-backed forces. US forces will also continue operations against al-Qaida in the Arabian peninsula.

In order to rebuild American “moral leadership” Biden said he would also restore the US refugee programme, and announced an executive order that would raise the number of refugees accepted into the US in the first fiscal year of the Biden-Harris administration to 125,000. That is higher than the 110,000 accepted in the last year of the Obama administration, which had dwindled to less than 15,000 in the Trump administration.

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As Biden was speaking, US Immigration and Customs Enforcement (Ice) announced it had canceled a deportation flight to Cameroonian and Democratic Republic of Congo, while it conducted an investigation into allegations of abuse by Ice agents against the deportees. The announcement marked a significant change of approach since the Senate confirmation of a new homeland security secretary, Alejandro Mayorkas.

“The United States’ moral leadership on refugee issues was a point of bipartisan consensus for so many decades when I first got here,” Biden said. “We shine the light, the lamp, of liberty on oppressed people. We’re offering safe havens for those fleeing violence or persecution, and our example pushed other nations to open wide their doors as well.”

The distancing of Washington from Riyadh is one of the most conspicuous reversals of Donald Trump’s agenda, but it also marks a break with the policies pursued by Barack Obama, who had backed the Saudi offensive in Yemen, although he later sought to impose constraints on its air war.

A bipartisan majority in Congress had previously voted to cut off support to the Saudi campaign, citing the civilian death toll and the murder of the Washington Post columnist Jamal Khashoggi. But Trump used his veto to block the move.

The US will also freeze arms sales to Saudi Arabia, and name a special envoy to Yemen, to put more pressure on the Saudis and Emiratis and the Houthi forces they are fighting, to make a lasting peace agreement.

“We have spoken with both senior officials in the UAE and senior officials in Saudi Arabia,” said the national security adviser, Jake Sullivan, before the speech. “We are pursuing a policy of no surprises when it comes to these types of actions.”

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Trump and his secretary of state, Mike Pompeo, treated Saudi Arabia and its crown prince, Mohammed bin Salman, as a major ally in their campaign to cripple Iran. To that end, Pompeo used emergency powers to sidestep Congress to keep arms supplies flowing to the Gulf.

Pompeo’s successor, Tony Blinken, by contrast, spoke bluntly about Saudi culpability in the Yemen war. He has so far made more than 25 introductory calls to counterparts around the world, and the Saudi foreign minister has not been among them. Biden’s director of national intelligence, Avril Haines, pledged to produce a declassified account of Khashoggi’s killing, which is expected to incriminate the Saudi crown prince.

William Hartung, the director of the arms and security programme at the Centre for International Policy, welcomed Biden’s move, but he added: “The devil will be in the details.

“To be effective, the new policy should stop all arms sales to Saudi Arabia and the UAE, both proposed and in the pipeline, including maintenance and logistical support; increase humanitarian aid to Yemen and reverse the designation of the Houthis as a foreign terrorist organization, which severely undermines the ability of aid groups; and press Saudi Arabia and the UAE to commence a ceasefire and negotiate in good faith for an inclusive peace agreement,” Hartung said.

An elderly man walks past a damaged building in Aden, Yemen, in 2018.An elderly man walks past a damaged building in Aden, Yemen, in 2018.
An elderly man walks past a damaged building in Aden, Yemen, in 2018. Photograph: Nariman El-Mofty/AP

Blinken has said the terrorist designation of the Houthis, imposed by Pompeo in the last days of the Trump administration, would be urgently reviewed.

The US decision, if implemented fully, will increase pressure on the UK to suspend arms sales to Saudia Arabia. The arms manufacturer Raytheon has already removed some orders from its books, according to evidence given to the British arms control select committee this week.

Although the UK is not formally part of the Saudi coalition in Yemen, it does provide technical assistance to the Saudi air force , which the Ministry of Defence says is designed to help Saudi Arabia’s targeting meet standards of humanitarian law.

Anna Stavrianakis, professor of international relations at the University of Sussex, said: “The UK now risks looking even further out of step with EU member states and potentially with the USA, which leaves the UK looking very isolated. For a country that is very invested in being seen to be at the forefront of the rule of law and multilateral arrangements, I think that is a very dangerous position for the UK government to get itself into.”

But the UK will be deeply reluctant to follow the US lead since the UK has licensed at least £5.4bn worth of fighter jets, mainly Typhoons and missiles, since the air campaign began in 2015.

The Biden administration has also stated its intention to re-enter the 2015 nuclear deal with Iran, something that Riyadh has adamantly opposed.

However, Biden officials have indicated that re-entry may be slow and complicated, and the president did not mention it in his speech.

Biden indicated he would take a tougher line against Moscow than Trump, who consistently avoided criticism of Putin. While the administration moved quickly to extend the New Start arms control treaty with Russia, the president made clear that would not stop Washington pushing back on Russian threats and human rights abuses.

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“I made it clear to President Putin I am very different from my predecessor, and the days of the United States rolling over in the face of Russia’s aggressive actions – interfering with our elections, cyber-attacks, poisoning its citizens – are over. We will not hesitate to raise the cost on Russia, and defend the vital interests of our people,” the president said.

Biden’s first set-piece foreign affairs speech was made at the state department, in a gesture of appreciation for US diplomats who were often depicted as a hostile “deep state” by Donald Trump.

“You are at the centre of all that I intend to do. You are the heart of it,” Biden told US diplomats and civil service staff. “And in our administration, you’re going to be trusted and empowered to do your job.”