President Obama said Sunday that the U.S. military will begin aiding what has been a chaotic and ineffective response to the Ebola epidemic in West Africa, arguing that it represents a serious national security concern.

The move significantly ramps up the U.S. response and comes as the already strained military is likely to be called upon further to address militant threats in the Middle East. The 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 — demonstrating to the White House the urgency of the issue.

The epidemic, which has killed at least 2,100 people in five African countries, is unlikely to spread to the United States in the short term, Obama said Sunday on NBC’s “Meet the Press.” But if the United States and other countries do not send needed equipment, public health workers and other supplies to the region, that situation could change and the virus could mutate to become more transmissible, he said.

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

“We’re going to have to get U.S. military assets just to set up, for example, isolation units and equipment there,” he said, “to provide security for public health workers surging from around the world.”

As the worst Ebola outbreak in history unfolds in West Africa, The Post's Joel Achenbach explains how the deadly virus wreaks havoc on the human body. (Davin Coburn/The Washington Post)

Even so, he warned that it would still take months to control the epidemic.

Last week, leading international health officials said the window for getting the epidemic under control is closing. Doctors Without Borders, one of the groups most active since the outbreak began months ago, faulted world leaders with failing to recognize the severity of the crisis sooner and said charities and West African governments alone do not have the capacity to stem the epidemic. The U.S. military, with its enormous logistical capacity and extensive air operations, could address gaps in the response quickly.

The medical group has long ­opposed military involvement by governments, but its international president, Joanne Liu, said the situation had become so desperate that it was now appealing for military assets to provide critical logistical and operational support. Priorities include the mass expansion of isolation centers, air bridges to move personnel and equipment to and within the most affected countries, mobile laboratories for testing and diagnosis, and building a regional network of field hospitals to treat suspected or infected medical personnel.

Only the military, Liu said in an interview Friday, has the rapid- deployment capability and chain-of-command structure necessary now. “Because the response has been so slow, we now have to switch to a mass-casualty response,” she said.

Ghana, for example, has agreed to make the international airport in Accra an air bridge for Ebola responses. Experts say the U.S. Air Force would be well suited to supply transport flights and personnel, as well as warehousing and logistics support at the airport.

The United Nations said last week that $600 million will be needed to fight the epidemic and deal with the broader economic and social devastation suffered by the hardest-hit countries — Liberia, Sierra Leone and Guinea.

The U.S. government has spent more than $100 million in the region, according to Ned Price, a spokesman at the National Security Council. Last week, the U.S. Agency for International Development announced plans to make an additional $75 million available. More than 100 experts, most of them from the U.S. Centers for Disease Control and Prevention, are deployed to the region in an effort to prevent, detect and halt the virus’s spread.

The Ebola epidemic over time

The Obama administration has also asked Congress for an additional $88 million to send more CDC personnel and lab supplies and equipment, Price said. The United States is providing logistical and operational support, including hundreds of thousands of units of personal protective equipment, mobile labs, water-treatment units, disinfectant, basic supplies and food assistance, he said. If Congress approves the additional funding, it will bring the U.S. total commitment to more than $250 million.

U.S. officials have been in talks with international organizations and aid groups. They declined to provide details of the military involvement outlined by the president. The Defense Department has already provided lab equipment, supplies and staff in Liberia. Military planners are also on the ground in the region to assess “how their unique capabilities can be used to improve logistics, provide lift capacity and increase treatment options,” said a senior administration official who spoke on the condition of anonymity because planning is still underway.

A senior Defense Department official who was not authorized to comment publicly said the Pentagon has been supporting U.S. aid efforts and international organizations since the outbreak began. The department is “now working to fulfill a request to provide rapidly deployable medical treatment facilities that will help increase the capacity of the aid workers in West Africa,” he said.

Such facilities are akin to field hospitals that can treat several dozen people. At the moment, the defense official said, there are no requests to provide guns.

Outside experts have also been calling for an increased military effort and welcomed Obama’s announcement. “For several weeks there has been cross-talk, off the record, in Washington, and health advocates have urged the military to commit its resources to the Ebola crisis,” Laurie Garrett, senior fellow for global health at the Council on Foreign Relations, said in a statement Sunday. She is the author of “The Coming Plague,” which described the original Ebola outbreak in 1976 in Zaire, now known as Congo.

“The logistics and medical capacities of the U.S. Armed Forces are the best any military in the world has to offer — battle-tested, highly professional, extremely skilled,” she said. Detailed decisions have not yet been made, Garrett said.

But she said Obama’s comment signals “that — at last — we’re moving from ‘should we’ to ‘how much, where, and doing what’ — and this could be a game-changer.”

In its most recent update, on Friday, the World Health Organization said the death toll from the outbreak had soared past 2,000, with nearly 4,000 reported infected in West Africa. Those numbers are widely believed to represent only a portion of total cases. The fatality rate has varied widely — from 39 percent in Sierra Leone to 64 percent in Guinea — but averages more than 50 percent overall.

Whatever help arrives will not come too soon. Infections have mounted rapidly in recent days, and the situation in many places in West Africa has grown more uncertain, chaotic and desperate. Authorities in Sierra Leone said over the weekend that they would require people there to stay home for several days later this month to slow the disease’s spread. Health workers have raised concerns about that approach, saying it could prevent them from identifying and treating victims.

There was some confusion Sunday about Obama’s comments regarding the use of military assets to “provide security for public health workers surging from around the world.”

In an interview Sunday, Brice de le Vingne, director of operations for Doctors Without Borders, said he welcomed the increased U.S. response but was concerned about the security reference. Doctors Without Borders is not asking for military personnel to help with security, only logistics support, he said. It has 2,000 staffers working in the three countries. “We don’t have any security problems or constraints,” he said.

But the need for beds in isolation units is dire. In Monrovia, Liberia, where the disease is escalating exponentially daily, the group needs 800 to 1,000 isolation beds, de le Vingne said. The group’s current capacity there is between 150 and 180 beds.

“In the city, it is a catastrophe today,” he said. “We have people dying at our doorsteps at our treatment centers.”

Brady Dennis contributed to this report.