Vice President Harris is heading to Warsaw on Wednesday for a trip meant to show unity with Poland and Romania, two U.S. allies that flank Ukraine.

But the visit comes a day after an unusually public disagreement over a Polish proposal to share its fighter jets with Ukraine — an idea that the Pentagon rejected.

Senior administration officials who briefed reporters ahead of Harris’ trip downplayed the dispute, saying that there were “a lot of ideas worth discussing” even though this one was judged “not tenable” by the Pentagon, and noting that talks would continue while Harris was overseas.

Poland surprised the U.S. with its proposal

Ukrainian President Volodymyr Zelenskyy asked U.S lawmakers on Saturday for help getting more Russian-made MiG fighter jets to his military — jets that his pilots know to how to fly.

The White House said it would try to work to help Ukraine get them from Poland — replacing the jets with U.S.-made aircraft for Poland — but said it would be hard to transfer planes into Ukraine.

Then on Tuesday, Poland announced it would send its jets to the U.S. air base at Ramstein, Germany. That caught U.S. officials off guard. Later in the day, the Pentagon issued a statement saying flying planes from a U.S./NATO base in Germany into contested airspace wouldn’t work.

“It is simply not clear to us that there is a substantive rationale for it,” Pentagon spokesman John Kirby said. “We will continue to consult with Poland and our other NATO allies about this issue and the difficult logistical challenges it presents, but we do not believe Poland’s proposal is a tenable one.”

Harris will meet with Polish officials on Thursday

Harris’ trip was planned well before the disagreement happened. She has been meeting and talking with NATO allies on the alliance’s eastern flank even before Russia invaded Ukraine, and plans to discuss “next steps” to respond to Russian aggression, officials told reporters.

On Thursday, she will hold meetings with Polish President Andrzej Duda and Prime Minister Mateusz Morawiecki — as well as with Canadian Prime Minister Justin Trudeau, who happens to be visiting Warsaw at the same time.

Officials said Harris will meet Ukrainians who have fled their country, as well as U.S. embassy staff from Kyiv, who are now based in Poland because of the conflict.

On Friday, Harris will meet with Romania’s president in Bucharest

Harris will meet U.S. service members stationed in Poland on Friday before she heads to Bucharest to meet Romanian President Klaus Iohannis.

The United States has boosted its troop presence in Poland and Romania to reinforce NATO allies. Harris wants to talk about how the U.S. can provide support for refugees. More than half of the 2 million people who have fled Ukraine are in Poland.

LONDON — Britain shattered its record for highest temperature ever registered Tuesday amid a heat wave that has seized swaths of Europe — and the national weather forecaster predicted it would get hotter still in a country ill prepared for such extremes.

The typically temperate nation was just the latest to be walloped by unusually hot, dry weather that has gripped the continent since last week, triggering wildfires from Portugal to the Balkans and leading to hundreds of heat-related deaths. Images of flames racing toward a French beach and Britons sweltering — even at the seaside — have driven home concerns about climate change.

The U.K. Met Office registered a provisional reading of 40.2 degrees Celsius (104.4 degrees Fahrenheit) at Heathrow Airport — breaking the record set just an hour earlier. Before Tuesday, the highest temperature recorded in Britain was 38.7 C (101.7 F), a record set in 2019.

The nation watched the mercury rise with a combination of horror and fascination. With several hours of intense sunlight ahead, the record could go even higher.

“Temperatures are likely to rise further through today,” the forecaster said after the first record fell.

The sweltering weather has disrupted travel, health care and schools in a country not prepared for such extremes. A huge chunk of England, from London in the south to Manchester and Leeds in the north, remained under the country’s first “red” warning for extreme heat Tuesday, meaning there is danger of death even for healthy people.

London streets saw less traffic, as many heeded advice to stay out of the sun, and trains ran at low speed out of concern rails could buckle, or did not run at all. The British Museum — which has a glass-roofed atrium — planned to shut its doors early. And the Supreme Court closed to visitors after a problem with the air conditioning forced it to move hearings online.

Many public buildings, including hospitals, don’t even have air conditioning, a reflection of how unusual such extreme heat is in the country better known for rain and mild temperatures.

The capital’s Hyde Park, normally busy with walkers, was eerily quiet — except for the long lines to take a dip in the park’s Serpentine lake.

“I’m going to my office because it is nice and cool,” said geologist Tom Elliott, 31, after taking a swim. “I’m cycling around instead of taking the Tube.”

London’s King’s Cross Station, one of the country’s busiest rail hubs, was empty on Tuesday, with no trains on the typically bustling east coast line connecting the capital to the north and Scotland. London’s Luton Airport closed its runway for several hours Monday because of heat damage.

Transport Secretary Grant Shapps said Britain’s transport infrastructure, some of it dating from Victorian times, “just wasn’t built to withstand this type of temperature — and it will be many years before we can replace infrastructure with the kind of infrastructure that could.”

The dangers of extreme heat were on display in Britain and around Europe. At least six people were reported to have drowned across the U.K. in rivers, lakes and reservoirs while trying to cool off. Meanwhile, nearly 750 heat-related deaths have been reported in Spain and neighboring Portugal in the heat wave there.

The highest temperature previously recorded in Britain was 38.7 C (101.7 F), a record set in 2019. Tuesday’s reading was provisional, which means they are produced as near to real time as possible with final readings issued after data quality-control, the Met Office said.

Climate experts warn that global warming has increased the frequency of extreme weather events, with studies showing that the likelihood of temperatures in the U.K. reaching 40 C (104 F) is now 10 times higher than in the pre-industrial era. In fact, that once unthinkable mark looked possible — even likely — Tuesday.

“This record temperature is a harbinger of things to come,” said Bob Ward of the Grantham Research Institute at the London School of Economics. “The increase in the frequency and intensity of heat waves and other extreme weather events is the result of climate change, and these impacts will continue to grow” unless the world drastically reduces emissions.

Drought and heat waves tied to climate change have also made wildfires harder to fight.

In the Gironde region of southwestern France, ferocious wildfires continued to spread through tinder-dry pines forests, frustrating firefighting efforts by more than 2,000 firefighters and water-bombing planes.

More than 37,000 people have been evacuated from homes and summer vacation spots since the fires broke out July 12 and burned through 190 square kilometers (more than 70 square miles) of forests and vegetation, Gironde authorities said.

A smaller third fire broke out late Monday in the Medoc wine region north of Bordeaux, further taxing firefighting resources. Five camping sites went up in flames in the Atlantic coast beach zone where blazes raged, around the Arcachon maritime basin famous for its oysters and resorts.

But weather forecasts offered some consolation, with heat-wave temperatures expected to ease along the Atlantic seaboard Tuesday and the possibility of rains rolling in late in the day.