Trump Downplayed the Leak of Military Plans

President Trump told reporters today that the disclosure of internal national security deliberations on a commercial messaging app was a minor transgression. He characterized the extraordinary security breach as “just something that can happen.”

Trump also stood by his national security adviser, Michael Waltz, who had inadvertently added a journalist to a group chat with other members of the president’s inner circle. In the chat, Defense Secretary Pete Hegseth and others shared information on timing, targets and weapons systems to be used in an attack on Houthi militants in Yemen. Here’s what to know about it.

During a Senate hearing this morning, the nation’s top two spy chiefs — who were both in the chat — acknowledged the sensitivity of information shared, but rejected responsibility. The administration claimed that nothing classified was shared; the journalist who was included in the chat said “they are wrong.”

Either way, disclosing even nonclassified national defense information in a nonsecure setting — like the app that was used, Signal — can still violate the 1917 Espionage Act.

Ukraine and Russia agreed to stop fighting in the Black Sea

The Trump administration announced today that it had helped broker a maritime cease-fire, in which both Ukraine and Russia would halt fighting in the Black Sea. Both countries confirmed the agreement, a significant step in the three-year war, but still far short of the permanent truce that Trump has been pushing for.

The deal, which came after three days of negotiations in Saudi Arabia, appeared to extract no major concessions from Russia, which started the war. The Kremlin said it would honor the maritime truce only after restrictions on Russian agricultural exports were removed — a demand the White House appeared to agree to, at least in part.

In other news from Ukraine, a cheap drone punched a hole last month in Chernobyl’s 40,000-ton shield — which had been intended to enclose the nuclear disaster site for a century.

The Social Security nominee vowed not to seek privatization

Frank Bisignano, the Wall Street veteran being considered to lead the Social Security Administration, offered a “guarantee” at his Senate confirmation hearing today that he would not seek to privatize the program: “I’ve never thought about privatizing,” he said.

Bisignano’s nomination appeared to have enough Republican support to advance through the committee. His role has come under tense scrutiny as Elon Musk has become fixated on finding fraud inside the agency, which provides retirement, survivor and disability payments to 73 million Americans each month.

In other politics news:

A Kennedy-backed remedy left some measles patients sicker

Doctors in West Texas are seeing measles patients whose illnesses have been complicated by an alternative therapy endorsed by vaccine skeptics, including Robert F. Kennedy Jr., the health secretary.

Parents in the region have increasingly turned to unproven treatments to protect their children, many of whom are unvaccinated, against the virus. Local doctors say they have now treated a handful of children who were given so much vitamin A — which Kennedy has promoted as a near-miraculous cure for measles — that they showed signs of liver damage.

A look inside the world of Yoko Ono

The writer David Sheff is out today with “Yoko” — a new biography of Yoko Ono, the artist and widow of the murdered rock star John Lennon. Ono has long been reviled as the woman who broke up the Beatles, and Sheff’s book is the latest in a series of recent corrective works looking to reshape her legacy.

What makes Sheff’s contribution stand out, our critic Alexandra Jacobs writes, is that he is good friends with Ono. His portrait is sympathetic, but convincing: Ono, Sheff argues, is a survivor, a feminist, an avant-gardist, a political activist and a world-class sass.

‘Adolescence’ has people talking

The new series “Adolescence,” about a 13-year-old British boy suspected of killing a girl after being exposed to misogynist ideas, has for the last two weeks been Netflix’s most-watched show in dozens of countries, including the U.S. It has also reignited debate about restricting children’s access to smartphones.

In Britain, where officials have warned of online harm gangs, lawmakers have used “Adolescence” to argue that the country should crack down on social media use among children.

Not your average ice queen

Amber Glenn is the top women’s figure skater in the U.S. She has landed the supremely challenging triple axel in all her competitions this season, earning her an undefeated record and securing her the chance to become the first American woman to win a World Championship title in nearly 20 years.

But Glenn is unlike her sport’s typical stars. She is openly pansexual; she jumps like a pole-vaulter; she models her hair off the pop star Kesha; she collects lightsabers and Magic: The Gathering cards. She is also 25 — an age when most of her peers have long since retired.

Have an atypical evening.

Thanks for reading. I’ll be back tomorrow. — Matthew

Philip Pacheco was our photo editor today.

We welcome your feedback. Write to us at evening@nytimes.com.