President Donald Trump’s decision to halt funding for the World Health Organization, depriving it of its biggest funding source, could have far-reaching effects in efforts to fight diseases and make health care more widely available across the globe.

Trump’s order centered on the organization’s response to the coronavirus pandemic, and he is far from alone in criticizing its actions and statements. Some countries have disregarded the WHO’s efforts as the epidemic has spread, failing to report outbreaks or flouting international regulations.

But the WHO is responsible for much more than epidemic response, and it now finds itself financially imperiled by its newfound place in the cross-hairs of U.S. domestic politics.

Here are answers to some common questions about the organization.

What does the World Health Organization do?

Founded after World War II as part of the United Nations, the Geneva-based organization, which has about 7,000 workers spread over 150 offices worldwide, has no direct authority over member nations. Instead, it is intended to be an international leader in public health by alerting the world to threats, fighting diseases, developing policy and improving access to care.

During emergencies like the coronavirus, the WHO is meant to serve as a central coordinating body — guiding containment, declaring emergencies and making recommendations — with countries sharing information to help scientists address outbreaks.

Though the WHO is broadly influential, it lacks meaningful enforcement authority and is under budgetary and political pressures, especially from powerful nations like the United States and China and private funders like the Gates Foundation.

António Guterres, the U.N. secretary-general, defended the WHO in a statement Tuesday, saying it “must be supported, as it is absolutely critical to the world’s efforts to win the war against COVID-19.”

He said it is “not the time to reduce the resources for the operations of the World Health Organization or any other humanitarian organization in the fight against the virus.”

How is it funded?

Financing comes from participating nations and private foundations. The United States is the largest contributor, making up 14.67% of its budget.

Member dues make up about a quarter of the money the United States gives the WHO; they are calculated relative to a nation’s wealth and population. The rest comes from voluntary contributions, which can vary in size year to year.

In 2019, the United States contributed about $553 million. The WHO’s biennial budget — every two years — was about $6.3 billion in 2018-2019.

Most of the money from the United States goes toward programs like polio eradication, developing vaccines and increasing access to essential health and nutrition services. Just 2.97% of the U.S. contribution goes toward emergency operations, and 2.33% is earmarked for outbreak prevention and control.

Lawrence O. Gostin, director of the O’Neill Institute for National and Global Health Law at Georgetown University, said about 70% of the funding from the United States has gone to programs that it has earmarked, such as those directed toward AIDS, mental health programs, cancer and heart disease prevention.

“The highest profile is on epidemic control and preparedness,” he said. “But it is actually the least important thing WHO has done historically.”

The U.S. contribution is nearly twice the next-largest contribution from a nation, the United Kingdom, which funds 7.79% of the WHO budget. The Bill and Melinda Gates Foundation pays for 9.76% of the budget.

Why have Trump and others criticized it?

The president has accused the WHO of responding too slowly to the threat of the virus and not being critical enough of China. (The same accusations have been leveled at Trump, who was warned in January about a possible pandemic and who repeatedly praised the Chinese government for its handling of the virus.)

The WHO has consistently advised against travel restrictions, arguing that they are ineffective, can block needed resources and are likely to cause economic harm. But Trump has frequently pointed to his decision to limit travel from China in late January as evidence he took the threat seriously.

But Trump is not alone in his criticism. Some experts have said the WHO was slow to declare a public health emergency and was too trusting of the Chinese government, which initially tried to conceal the extent of the outbreak, as the country has gained influence in the organization.

Trump’s decision to halt funding appears to be the first such formal announcement of its kind by an American president, experts said, though the United States has had a sometimes contentious history with the WHO on issues like breastfeeding and tobacco.

Dr. Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security, said there were legitimate concerns about the need for reforms at the WHO. Some member states have undue influence over the organization’s messaging, and after the Ebola outbreak that began in 2013, regional offices were seen as having inadequate autonomy to respond to the emergency, he said.

“There is room to criticize here,” he said. “But I don’t think, in the middle of a pandemic, making a political statement is the best way to address the shortcomings.”

Gostin said that the organization has been hobbled for structural and political reasons, and become timid as a result.

“The fact that President Trump is withholding or curtailing funding is exactly the prime example of why we are in this mess,” he said. “The director general is worried that any time he puts a move wrong, they will withdraw funding or undercut the agency politically.”

What has the WHO said and done about the coronavirus?

Throughout January, the WHO issued advisories about the dangers of the virus. From Jan. 22 on, Dr. Tedros Adhanom Ghebreyesus, the WHO’s director general, held almost daily news briefings to warn the world that the virus was spreading, and that the window of opportunity to stop it was closing.

But the organization initially hesitated to declare a global health emergency even as the virus spread outside of China.

“This is an emergency in China, but it has not yet become a global health emergency,” Tedros said Jan. 23. “It may yet become one.” On Jan. 30, the WHO made the official declaration, which often prompts governments to take action. Soon afterward, the State Department warned travelers to avoid China.

For weeks, the WHO issued guidance and warnings, and it officially declared the outbreak a pandemic on March 11, calling on governments to work together to battle the virus. Critics said both its declarations came too late, and that earlier decisions could have mobilized governments more quickly. While the WHO is intended to coordinate the worldwide response, there has been little global solidarity, showing the limits of its power. The organization had a plan, but few countries have hewed to it.

Gostin said that in the long run, the president’s decision to cut the funding could lead to a restructuring of the WHO, with new international leadership, new health alliances, and greater control over its budget.

He said the United States has also been “a thorn in the side” of the WHO over the years, blocking some of its efforts on access to medicines or watering down global action plans on migrants and refugees.

But he added: “I think that President Trump in this singular act has taken a step too far.”

“This will enormously erode American influence in the world and in global health and international affairs in the midst of an epidemic of unprecedented scope,” he said. “We will lose our voice, and even our influence, even with our allies. I don’t think we get a say anymore with how this unfolds.”