U.S. military and U.S. Public Health Service members unload cargo at the Monrovia Medical Unit on Nov. 4 in Liberia.(Michel du Cille/The Washington Post)

The number of U.S. troops deploying to West Africa to help battle the Ebola epidemic could grow to 3,000 by the middle of December, but likely will not expand to the 4,000 soldiers that military officials had expected to send just weeks ago.

“What we found working with (the U.S. Agency for International Development) and the government of Liberia was there’s a lot of capacity here that we didn’t know about before,” Maj. Gen. Gary Volesky, who commands the U.S. military’s Ebola response in Liberia, said in a telephone briefing Wednesday with reporters at the Pentagon. “And so that enabled us to reduce the forces that we thought we originally had to bring.”

The decision not send the full number of U.S. troops initially authorized comes as the rate of Ebola infections has fallen sharply in Liberia in recent weeks, leaving once-overwhelmed treatment centers half empty and some corners of the country with few or no new cases. At the same, despite the recent positive turn in Liberia, infections have spiked in Sierra Leone, as well as in parts of Guinea.

Volesky and other officials involved in the U.S. effort against Ebola said that while the number of new cases in Liberia had slowed, the disease continues to pose a serious threat, and plenty of work remains to break the transmission chain of the disease.

“We are not out of the woods by any stretch of the imagination,” said Deborah Malac, the U.S. ambassador to Liberia. She said more treatment units and medical personnel were still needed to quell the outbreak.

Volesky said he expected that all 17 Ebola treatment units the United States had vowed to build in Liberia would be finished by the end of December. In addition, Malac said officials are working to reverse widespread public skepticism of Liberia’s health system, which had contributed to an increase in deaths from other, unrelated problems as many Liberians stayed away from medical facilities after the Ebola outbreak took root. .

“The system collapsed under the weight of this epidemic, which was much broader and faster than anybody could have anticipated, partly out of fear,” she said.

Related: Will U.S. Ebola fighters’ effort be enough?