The White House has chosen a deputy of Robert F Kennedy Jr to serve as the acting head of the US Centers for Disease Control and Prevention (CDC), a decision that comes as lawyers for the fired director, Susan Monarez, claim she will not depart unless Donald Trump himself removes her.

A White House official confirmed to the Guardian that Jim O’Neill, the deputy secretary of the Department of Health and Human Services (HHS), had been selected to temporarily lead the public health agency, giving Kennedy an ally in his efforts to overhaul US vaccine policy.

The decision to remove Monarez has sparked further turmoil within the CDC. Four other senior leaders resigned over what they condemned as political interference in their work, budget cuts and the spread of misinformation under the Trump administration.

What’s O’Neill’s background? Unlike Monarez, O’Neill does not have a medical or scientific background. He is a former investment executive, served as a speechwriter for the health department during the George W Bush administration, and went on to work for the tech investor and conservative mega-donor Peter Thiel.

Democrats seek ‘immediate answers’ after reported arrests of firefighters by US border agents

View image in fullscreen The Trump administration’s immigration policy was ‘fundamentally sick’, Patty Murray said. Photograph: Annabelle Gordon/UPI/Rex/Shutterstock

Patty Murray, the Washington senator, has called for the Trump administration to provide “immediate answers” about reports that two firefighters were detained by border agents as they were responding to a wildfire in the state.

Federal immigration authorities on Wednesday staged an operation on the scene of the Bear Gulch fire, a nearly 3,600-hectare (9,000-acre) blaze in the Olympic national forest, where they arrested two people who were part of a contract firefighting crew, the Seattle Times first reported. The fire is the largest burning in the state.

Authorities made the firefighters line up to show identification, the newspaper reported. One firefighter said they were not permitted to say goodbye to their detained colleagues.

What did Murray say? The Trump administration’s immigration policy was “fundamentally sick”, Murray said. “Trump has wrongfully detained everyone from lawful green-card holders to American citizens – no one should assume this was necessary or appropriate.”

Trump faces key legal test in effort to exert control over Federal Reserve

View image in fullscreen Donald Trump has repeated allegations that Lisa Cook lied on a mortgage application in an attempt to oust her from the Fed’s board of governors. Photograph: Saul Loeb/AFP/Getty Images

Donald Trump’s battle to exert control over the Federal Reserve faces a key legal test today, with a governor of the central bank seeking a temporary block on his extraordinary attempt to fire her.

Lisa Cook sued the US president yesterday, with her lawyers describing his attempt to dismiss her as “unprecedented and illegal”, and based on “pretextual” allegations.

The case is widely expected to be ultimately decided by the supreme court. While it makes it way through the courts, Cook is seeking a temporary restraining order against Trump’s attempt to dismiss her “immediately” from the Fed’s board.

Why has Trump been attacking the Fed? Most of the Fed’s policymakers, including Cook, have so far defied Trump’s calls for interest rate cuts. He has spoken of rapidly building a “majority” on the central bank’s board, calling into question the future of its longstanding independence from political oversight.

In other news …

View image in fullscreen Alejandro ‘Alito’ Moreno (L) and Gerardo Fernández Noroña grabbed and shouted at each other about the presence of foreign troops. Photograph: AFP/Getty Images

Mexico’s senate descended into violence as two of the country’s top politicians shoved, grabbed and shouted at each other after a heated discussion about the presence of foreign troops.

The US tariff exemption for package shipments valued under $800 officially ended today , raising costs and disrupting supply chain models for a range of businesses.

Russian missile strikes on Kyiv killed at least 23 people and damaged the British Council and EU delegation offices , in the deadliest aerial assault on the Ukrainian capital since the Alaska summit between Vladimir Putin and Donald Trump.

A judge ordered a new trial for three former police officers who were convicted in the fatal beating of Tyre Nichols, a young Black man whose death prompted intense scrutiny of Memphis police, nationwide protests and renewed calls for police reform.

Stat of the day: Humans inhale as much as 68,000 microplastic particles daily, study finds

View image in fullscreen Among other issues, microplastics are linked to chronic pulmonary inflammation, which can lead to lung cancer. Photograph: pcess609/Getty Images/iStockphoto

Every breath people take in their homes or car probably contains significant amounts of microplastics small enough to burrow deep into the lungs, peer-reviewed research has found, bringing into focus a little-understood route of exposure and health threat.

Don’t miss this: ‘Hash court’ and high drama – how weed became the US Open’s new distraction

View image in fullscreen One player has likened court 17 to ‘Snoop Dogg’s living room’ due to the smell of marijuana. Photograph: Clive Brunskill/Getty Images

The US Open has always been the unruliest of tennis’s four grand slam tournaments, a place where the soundtrack is as much screeching trains, the roar of air traffic overhead and well-lubricated crowds as it is the thwack of racket on ball. In recent years, though, one distraction has cut through even the normalized bedlam that gives the tournament its character: the pungent and unmistakable odor of marijuana.

Climate check: Heatwaves, wildfires and the hot summers that could change tourism

View image in fullscreen It’s hard to relax by the beach in 40C heat with the stench of smoke fouling the air. Photograph: Steve Parsons/PA

With rising temperatures causing chaos worldwide, what does it mean to be a tourist in a world on fire? Holiday hotspots are being ravaged by heat, fire, floods and drought as fossil fuel pollution warps the climate. Stefan Gössling, one of the most-cited travel researchers in the world, recently declared the approaching demise of the era of mass tourism.

Last Thing: Unhinged tweets and absurd self-promotion? Two can play at that game

View image in fullscreen ‘It’s too bad, of course, that insults and absurd memes have become the American way. But at least Newsom, and his social media team, are awfully good at it.’ Photograph: Fred Greaves/Reuters

All-caps tweets with nonsensical punctuation? Insulting nicknames for political enemies? Self-promotional merchandise for sale? Gavin Newsom, the governor of California, has spent the last few weeks mercilessly trolling Trump and his Maga followers by flipping the script.

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