President Obama will announce Tuesday that the U.S. military will take the lead in overseeing what has been a chaotic and widely criticized response to the worst Ebola outbreak in history, dispatching up to 3,000 military personnel to West Africa in an effort that could cost up to $750 million over the next six months, according to senior administration officials.

By the end of the week, a general sent by U.S. Africa Command will be in place in Monrovia, Liberia — the country where transmission rates are increasing exponentially — to lead the effort called Operation United Assistance. The general will head a regional command based in Liberia that will help oversee and coordinate U.S. and international relief efforts while a new, separate regional staging base will help accelerate transportation of urgently needed equipment, supplies and personnel.

In addition, the Pentagon will send engineers to set up 17 treatment centers in Liberia — each with a 100-bed capacity — as well as medical personnel to train up to 500 health-care workers a week in the region.

The president’s decision to enlist the U.S. military, whose resources are already under strain as it responds to conflicts in the Middle East, reflects the growing concern of U.S. officials that, unless greater force is brought to bear, the epidemic could wreak havoc on the continent.

“It’s this broad range of capabilities together that will turn the tide of this epidemic,” said one senior administration official, who along with others spoke on the condition of anonymity in order to discuss the president’s plan in advance of Obama’s trip to the Centers for Disease Control and Prevention in Atlanta on Tuesday.

President Obama announced Tuesday that the U.S. will lead efforts to combat the Ebola outbreak in West Africa, pledging to dispatch 3,000 military personnel to the region. (WhiteHouse.gov)

Global health experts and international aid groups who have been urging the White House to dramatically scale up its response praised the plan as described. They have said charities and West African governments alone do not have the capacity to stem the epidemic.

The U.S. military, with its enormous logistical capability, extensive air operations, and highly skilled medical corps, could address gaps in the response quickly.

“This is a really significant response on the military side,” said Laurie Garrett, senior fellow for global health at the Council on Foreign Relations and author of a book about the first Ebola outbreak in 1976 and another on the global public-health system. “This is really beginning to seem like a game-changer.”

But much depends on how quickly personnel and supplies can get there.

“The problem is, for every single thing we’re doing, we’re racing against the virus, and the virus has the high ground right now,” she said. “I would hope this would reduce transmission, but it’s all about how fast people can get there and get the job done. If it takes weeks to mobilize, the strategy won’t even be within reach.”

Although the official death toll is at least 2,400 people in five African countries, officials say it vastly underestimates the true caseload. Garrett, who has been talking to health-care workers in the region, said the cumulative total, including deaths, could reach 250,000 by Christmas.

A senior official cautioned that the efforts “won’t happen overnight.” It will be several weeks before training of health-care workers can be up and running.

At a briefing Monday, White House press secretary Josh Earnest said Obama is visiting the CDC to get an update from the experts there “about the success of their efforts so far to try to confront this problem. . . . And that is the strategy that we’re implementing here, is to try to invest early to prevent this from becoming much more serious.”

Washington has come under fire from African officials — especially in the hardest-hit countries of Liberia, Sierra Leone and Guinea — and on Capitol Hill for not marshaling more of its resources to combat the epidemic.

The United States has already spent $175 million responding to the outbreak and has dispatched 100 CDC experts, among the largest deployments of agency personnel in its history. The administration has sought an additional $88 million and may ask for more, according to a senior administration official. “I don’t want to close the door to potential additional funding,” the official said. Separately, the Pentagon wants to take up to $500 million from existing funds within the Pentagon’s budget that have not yet been spent and use it for the plan to fight Ebola.

The Pentagon announced last week that it would send a 25-bed hospital to Liberia. The hospital is designed to care for health-care workers who become ill, and eventually will be turned over to the Liberian government. It will be at least a month before the hospital is up and running. The United States Public Health Service Commissioned Corps is preparing to deploy 65 Commissioned Corps officers to Liberia to manage and staff the hospital.

The United States has already set up one mobile laboratory, and another two are on the way.

In addition to expanding treatment and training facilities, the United States will send enough basic Ebola response kits to supply 400,000 households in Liberia, according to a senior administration official. That is intended to address an increasingly common phenomenon in which sick patients are being denied access to overflowing treatment centers and being sent home.

The packages, which include sanitizers, will help curb transmission of the disease among family members and expand access to ambulances and treatment centers so those infected can be isolated. As part of this effort, the U.S. Agency for International Development this week will airlift 50,000 home health-care kits from Denmark to Liberia to be hand-delivered to distant communities by trained youth volunteers.

The administration’s decision to involve the military in providing equipment and other assistance for international health workers in Africa comes after mounting calls from some unlikely groups — most prominently the international medical organization Doctors Without Borders — pressed the urgency of the issue.

While the world’s largest international health organizations, several governments and many nonprofits have already devoted significant resources to addressing the virus outbreak, administration officials said Monday that they had concluded that the United States would have to lead more aggressively in order to check Ebola’s spread. In Liberia’s capital, patients are dying on the street because there aren’t enough beds in treatment centers.

“Our concern is if we do not arrest that growth, and we don’t arrest that growth now, we could be looking at hundreds of thousands of cases” in Africa, the official said, noting that it will still take “months” to reduce the numbers of illnesses and deaths from the disease.

The U.S. response drew cautious praise from Doctors Without Borders, which has been the most active group in the region, battling the epidemic for months.

“Although we have not yet seen the official details, we welcome the ambition of the new US Ebola response plan, which appears to match the scope of the disaster unfolding in West Africa,” Brice de le Vigne, the group’s director of operations, said in a statement. “This latest pledge, alongside those from a handful of other countries, needs to be put into action immediately.”

He said that the response to Ebola continues to fall “dangerously behind” and that too many lives are being lost.

“If implemented swiftly, the deployment of new Ebola management centers, qualified staff and health personnel training could begin reversing the trend of the fight we have collectively been losing against Ebola,” he said.

Even as officials emphasized the need for bolder action and said they were bolstering defenses within the United States, they said the chance of an Ebola outbreak here was “a very low probability.”

Public health experts in America “know how to contain this virus,” one official said. “If there is a case that appears in the United States, that person would be isolated [and] the appropriate protocols would be put in place such that it would contain that.”

To some extent, the measures that the president is now adopting have been called for by some of his critics. On Friday, Sen. Rob Portman (R-Ohio) called on Obama to appoint a “central coordinator” to oversee the federal government’s response to the disease.

Sen. Lamar Alexander (Tenn.), the top Republican on the Health, Education, Labor and Pensions Committee, said in a statement Monday, “This is an instance where we should be running toward the burning flames with our fireproof suits on.”

High-level planning by top officials from the CDC, the Pentagon, the State Department, USAID and the National Institutes of Health has been taking place for some time about options for a U.S. response, according to a senior administration official who spoke on background because planning was underway. The most recent high-level meeting was convened by Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staff, at the Pentagon last Wednesday.

Speaking on NBC’s “Meet The Press” on Sept. 7, Obama said that if the United States and other countries did not send equipment, health workers and other supplies to the region, the virus could mutate to become more transmissible.

“And then it could be a serious danger to the United States,” Obama said on the show.