Good morning.

       We’re covering Big Tech executives on the defensive, Vietnam’s mysterious surge in cases and a troubling trend in Latin American democracies.

       Big tech faces big questions Tech executives for the first time appeared together at an antitrust hearing into the U.S. tech industry on Wednesday that has been compared to U.S. efforts to minimize the power of tobacco companies.

       The chief executives of Google, Apple, Facebook and Amazon testified on whether their dominance has harmed the economy, stifled rivals and left consumers with few choices. All denied those claims.

       Jeff Bezos of Amazon, Tim Cook of Apple, Mark Zuckerberg of Facebook and Sundar Pichai of Google spoke by videoconference as members of Congress met in person on Capitol Hill.

       There were catchphrases, emotional speeches and technical issues. It was the culmination of a yearlong investigation into the companies by a committee of lawmakers. Many federal and state antitrust officials are also investigating the tech giants.

       We have live updates, and you can sign up for our On Tech newsletter for more insights.

       Go deeper: Jeff Bezos, the Amazon chief executive, has been cast in a role he never wanted: his company’s defender in Washington. He has taken an unusually hands-off approach with policymakers in the nation’s capital, our reporters write.

       What they said: We tallied how often the C.E.O.s repeated certain arguments and catchphrases, like “We are not that big” and “We are good for America.”

       How they looked: They may have trillions between them, but the C.E.O.s dressed to project humility, our fashion critic writes.

       Vietnam let down its guard, and cases surged It’s a familiar story in Asia: Vietnam seemed like a miracle, where months went by without a single coronavirus death or even local transmission.

       The economy reopened, travel restarted and residents began leaving their masks at home. But over the weekend, the country announced that the virus was lurking after all — and spreading. Experts do not know the source.

       It followed a pattern in places that seemed to have done everything right: Japan, China, Australia and South Korea all recorded spikes on Wednesday. And the mystery is worrying medical experts and residents alike.

       Details: Shortly after a 57-year-old man from Danang tested positive, clusters emerged in five hospitals. By Wednesday, the virus had spread north to Hanoi, south to Ho Chi Minh City, to two provinces in the country’s center and even the remote Central Highlands.

       Quotable: “In my opinion, this outbreak is more dangerous than the previous one because it is happening at the same time in many places,” said the dean of public health at Quang Trung University.

       Here are the latest updates and maps of the pandemic.

       In other developments:

       The U.S. virus death toll reached 150,000, by far the highest in the world, according to a New York Times database, as the rate of fatalities continued to rise in many areas.

       Hong Kong recorded 118 new cases on Wednesday, bringing the total tally past 3,000. Carrie Lam, the city’s leader, warned that a sharp rise in infections could lead to a “collapse” of the hospital system.

       Perrance Shiri has died of the coronavirus. The agriculture minister of Zimbabwe led a military unit that massacred thousands of civilians during civil strife in the 1980s and helped plot the coup that overthrew Robert Mugabe, the longtime leader. Mr. Shiri was 55.

       Australia’s government said it would send a specialist medical team usually deployed to disaster zones to help manage an outbreak in the state of Victoria.

       Hong Kong’s economy shrinks by 9 percent The fallout of the global pandemic has pulled the territory’s economy further into decline over the past three months, according to new data, which showed a 9 percent contraction.

       The new numbers showed a slight easing from January when the government reported the biggest drop in economic growth in four decades. Still, it was the fourth quarter of decline for the global financial hub.

       It comes after overlapping crises that dealt several blows to Hong Kong’s economy: a U.S.-China trade war, anti-government protests and a national security law imposed by Beijing, on top of the pandemic that battered spending, tourism and trade.

       Related: Second-quarter economic output for the U.S., to be released Thursday morning, is expected to be bad, our correspondent writes.

       If you have 5 minutes, this is worth it The virus chips away at Latin America’s gains

       Postponed elections. Sidelined courts. A persecuted opposition. Raids on the homes of journalists.

       As the pandemic tears through Latin America and the Caribbean, killing more than 180,000 and destroying livelihoods, it is also undermining democracy. Leaders are taking actions that under different circumstances would be described as authoritarian and antidemocratic but that now are being characterized as lifesaving measures to curb the spread of the coronavirus. Above, downtown Caracas, Venezuela, during lockdown.

       Here’s what else is happening Turkey: Lawmakers passed legislation on Wednesday that would give the government sweeping new powers to regulate social media content, raising concerns that it might be used to stifle dissent online.

       U.S. drawdown in Germany: The United States is cutting nearly 12,000 troops in Germany and shifting some around the continent, including relocating some units to Belgium and Italy, Defense Secretary Mark Esper announced. About 6,400 troops will return to the U.S.

       Notre Dame: Hundreds of tons of lead that burned in the April 2019 fire that nearly destroyed the cathedral in Paris landed in parks, buildings and playgrounds, and now some of it has made its way to the honey produced by urban beehives, researchers say.

       Snapshot: Above, a truck full of sheep crossing the border into Senegal from Mali. Ahead of the biggest holiday of the year, the Senegalese version of Eid al-Adha, they are in short supply amid coronavirus.

       What we’re listening to: This episode of “This American Life,” on figuring out how to be apart. “We’re all learning how to be alone during the pandemic, and the one thing we can take comfort in is that everyone is in that same boat,” writes Remy Tumin, a journalist on the Briefings team. She listened to this episode while on a solo walk around her neighborhood.

       Now, a break from the news

       Cook: These beef short rib rice bowls, inspired by galbi, the Korean barbecued short ribs, take a sharp turn away from the traditional sweet, fruity treatment and instead skew savory, with warm spices like cumin, coriander and turmeric.

       Read: Tana French has written seven novels, with an eighth due in October. All set in Ireland, the novels pull you way down rabbit holes and are haunting diversions, writes our literary critic, who has put together a guide for how to read her.

       Watch: Even though they were made before the pandemic, three new bold and chilling horror movies, all directed by women, have a kind of topical resonance now, with plots that deal with contagion and isolation.

       At Home has our full collection of ideas on what to read, cook, watch, and do.

       And now for the Back Story on … Our reporters on the U.F.O. beat Ralph Blumenthal and Leslie Kean were part of a Times reporting team that broke the story of the Advanced Aerospace Threat Identification Program, a secret unit of the Pentagon investigating unidentified flying objects, and they’ve been following the program ever since. Here’s an excerpt from what they wrote about covering U.F.O.s.

       We’re often asked by well-meaning associates and readers, “Do you believe in U.F.O.s?” The question sets us aback as being inappropriately personal. But in this case we have no problem responding, “No, we don’t believe in U.F.O.s.”

       And to be clear: U.F.O.s don’t mean aliens. Unidentified means we don’t know what they are, only that they demonstrate capabilities that do not appear to be possible through currently available technology.

       Our previous stories were relatively easy to document with Department of Defense videos of U.F.O.s and pilot eyewitness accounts backed up by Navy hazard reports of close encounters with small speeding objects.

       But our latest article provided a more daunting set of challenges, since we dealt with the possible existence of retrieved materials from U.F.O.s. We were provided a series of unclassified slides showing that the program took this seriously enough to include it in numerous briefings. One slide says one of the program’s tasks was to “arrange for access to data/reports/materials from crash retrievals of A.A.V.’s,” or advanced aerospace vehicles.

       Our sources told us that “A.A.V.” does not refer to vehicles made in any country — not Russian or Chinese — but is used to mean technology in the realm of the truly unexplained.

       That’s it for this briefing. See you next time.

       — Melina

       Thank you

       Carole Landry helped write this briefing. Theodore Kim and Jahaan Singh provided the break from the news. You can reach the team at briefing@nytimes.com.

       P.S.

       ？ We’re listening to “The Daily.” Our latest episode is about the Trump administration’s confrontation with China.

       ？ Here’s our Mini Crossword, and a clue: ___ x gravity x height = potential energy (four letters). You can find all our puzzles here.

       ？ Farah Stockman moves from the newsroom to the Opinion side as a writer covering foreign policy and national affairs.