America’s rivals celebrated as the Trump administration set out to dismantle its global influence and information infrastructure, including the media outlets that had helped market the United States as the world’s moral and cultural authority.

The editor in chief of RT, the Kremlin-backed news network, crowed about President Trump’s “awesome decision” to shut down Voice of America, the federally funded network that reports in countries with limited press freedom. “Today is a holiday for me and my colleagues!”

Hu Xijin, a former editor in chief of China’s state-run outlet Global Times, wrote that the paralysis of Voice of America and Radio Free Asia was “really gratifying” and, he hoped, “irreversible.” A top aide to Prime Minister Viktor Orban of Hungary posted that he “couldn’t be happier” about the administration’s move in February to gut the agency that distributed foreign media funding. Officials in Cambodia and Cuba also welcomed the cuts.

In the months since, China, Russia and other U.S. rivals have moved to commandeer the communications space abandoned by the Americans. They have pumped more money into their own global media endeavors, expanded social outreach programs abroad and cranked up the volume when publicizing popular cultural exports.

Foreign policy experts say the Trump administration is not just losing its grip on the global megaphone but handing it off to its eager adversaries. In doing so, they said, the United States is relinquishing its primacy as a global influencer and neglecting its defenses against the damaging narratives and disinformation that could fill the vacuum.

“What we’re doing, in a sense, is playing into their hands,” said Catherine Luther, a professor at the University of Tennessee, Knoxville, who has studied Russian influence. “These states tend to be the leaders in creating the playbook for other countries to use.”

The White House did not respond to a request for comment.

The United States was a pioneer of global message management, carefully cultivating its international reputation using movies, music, news, and other totems of culture and media to project aspirational American appeal. Supporting communications — through programs like Voice of America and grants for local independent outlets — has always been a key component of that so-called soft power.

But since January, the Trump administration has shut down a foreign influence task force at the Federal Bureau of Investigation, closed a State Department office that tracked and countered global disinformation, and crippled other teams that helped safeguard the American brand from overseas falsehoods and malign propaganda campaigns. A former Trump speechwriter who is currently acting as the under secretary for public diplomacy, a role intended to engage and understand foreign audiences, once posted that “competent white men must be in charge if you want things to work.”

The agency overseeing government-funded media outlets like the Radio Free stations and Voice of America, which reached hundreds of millions of people internationally each week, was gutted. A White House press officer reacted on X with a post listing “goodbye” in 20 languages. (A federal appeals court in Washington ruled last month that the Trump administration could continue for now to withhold funding from the stations, which have scaled back their operations. Instead, experts said, the Trump administration is focusing on other expressions of might, such as economic pressure and military force.)

“The soft power suicide of the U.S. will be incomprehensible to future historians who will be dumbfounded in their attempts to explain why the global leader voluntarily wrecked one of its greatest national assets,” wrote Jamie Shea, a British former official at the North Atlantic Treaty Organization and current senior fellow at Friends of Europe, a research institution.

Many global powers now see a better chance to “wage friendship,” as one researcher said, without competition from the United States.

Sputnik, a Kremlin-backed media outlet, opened an office in Ethiopia in February and said it was planning more in South Africa and possibly Tanzania. Turkey’s national public broadcaster, TRT, delivers online news in dozens of languages and started a broadcast channel in Somalia this spring.

Fahrettin Altun, Turkey’s head of communications, said last month that the broadcaster contributed to President Recep Tayyip Erdogan’s vision of a “Century of Turkey” by “being an alternative voice to the global media order” and pledged to help expand TRT’s “sphere of influence.”

In China, where global narrative domination has long been a public goal, the state news agency Xinhua said it had met with several Western media outlets in recent years to discuss distribution deals. China Daily, a state-run newspaper, increased its U.S. distribution budget in each of the past three years.

Chinese propaganda and disinformation campaigns have had spotty success resonating with foreign audiences. But Beijing has begun to recognize that the government is often not the most effective face for a charm offensive, said Shaoyu Yuan, a research fellow at Rutgers University’s Division of Global Affairs. Instead, global good will is frequently generated by social media influencers and private entrepreneurs, then amplified by state media and officials, he said. (The Chinese have faced some pushback on this front, as lawmakers in Washington take aim at imports such as TikTok, a popular video app, and DeepSeek, a chatbot app.)

Last year, Chinese state media lauded the video game Black Myth: Wukong, which is based on a classic Chinese novel, as a challenger to an industry dominated by American companies. Ne Zha 2, a record-smashing Chinese game about a mythological demon child, was hailed by the government as “a new window for the world to see China.”

Chinese apps streaming short soap operas are causing a stir in Hollywood, giving the country a way to reach new audiences through channels they created themselves, rather than through foreign media outlets, according to state media.

“The U.S. has definitely turned inward,” Dr. Yuan said. “It’s created a very big gap in global influence, and in China, both official and private groups have noticed this and are beginning to adjust their strategies accordingly.”

Ideals once championed by Americans are being propped up by other governments. In a gauge of trust among Southeast Asians that a Singaporean research organization released this spring, the United States fell to third place behind the European Union and Japan. Last month, the European Union promised $6.2 million in emergency support for Radio Free Europe. The British government said this year that it was creating a soft-power council to help elevate Britain’s global standing.

Members of the British Parliament sought extended funding for the BBC World Service this year, explaining that the broadcaster “plays an indispensable role in the fight against misinformation” and that “where services have been cut, we have seen other countries rush in to fill the space.” A poll commissioned by the BBC and conducted in 18 countries this past winter found that people who watched RT or CGTN, a Chinese state news outlet, were far more likely to say they viewed China or Russia favorably (and to hold nondemocratic views).

For decades, the United States telegraphed its influence and values abroad using an older communications infrastructure built on radio and text, and was slow to embrace the digital platforms that now connect much of the world. Voice of America has 727,000 followers on Instagram, where its last post is from 14 weeks ago, and Radio Free Europe/Radio Liberty have 44,500. China’s Xinhua News has 1.6 million followers, and BBC News has 29.2 million.

“When you declare ‘America First’ and you start berating your allies and friendly countries, you lose trust and you lose attraction,” Joseph S. Nye Jr., the American political scientist who coined the term “soft power,” said in an online briefing in March. (Mr. Nye died in May.)

Now, there are signs that the Trump team may be reconsidering its approach.

After Israel attacked Iran this month, dozens of Voice of America workers who had been put on leave were abruptly called back to reactivate the Voice of America news broadcast in Persian, which is the most common language spoken in Iran.

Over the following days, they produced dozens of videos and social media posts about the conflict, as well as several stories detailing the American role in possible peace talks and Mr. Trump’s timeline for considering military intervention.