The U.S. military operation against a ruthless guerrilla group accused of widespread atrocities is a short-term deployment with the specific goal of ending the threat of the Lord's Resistance Army in Africa, Obama administration officials insisted on Tuesday.

Facing skeptical members of the House Foreign Affairs Committee, administration officials said the roughly 100 American troops — mostly U.S. Army Special Forces — had been dispatched to central Africa as advisers to regional forces pursuing leader Joseph Kony and top commanders of the Lord's Resistance Army.

The U.S. designated the group a terrorist organization in 2001.

Alexander Vershbow, the assistant secretary of Defense for international security affairs, said the guerrilla group had been reduced to about 200 core fighters spread across vast jungle terrain in the Democratic Republic of the Congo, the Central African Republic and South Sudan. However, Kony and other commanders remain at large and continue to order atrocities. Combating this requires U.S. help with intelligence and coordination of operations.

"There are no doubt significant long-term challenges associated with building partner capacity in Africa, but this is a short-term deployment with specific goals and objectives," Vershbow told the committee. He later added: "If we think adjustments to the mission are warranted over time, we will consider them. If we do not believe our collective efforts are resulting in significant progress, we will not continue this deployment."

Pressed by lawmakers for a timetable, Vershbow said he couldn't offer any specifics, but "we're talking months. We will review in a few months."

Asked to define success, the Pentagon official said it was "capturing or killing Kony and other commanders." He also included defections from the guerrilla group.

Long considered one of Africa's most brutal rebel groups, the Lord's Resistance Army began its attacks in Uganda more than 20 years ago but has been pushing westward. The Obama administration and human rights groups say its atrocities have left thousands dead and have forced as many as 300,000 Africans to flee. They have charged the group with seizing children to bolster its ranks of soldiers and sometimes forcing them to become sex slaves.

Kony is wanted by the International Criminal Court for heinous attacks in multiple countries.

Earlier this month, President Barack Obama notified Congress that he was sending about 100 U.S. troops to central Africa to advise in the fight against the guerrilla group. Vershbow said they are carrying small arms for protection and communication systems as they operate in an advisory role.

Asked if the United States was authorized to use Predator drones, Vershbow said the use of drones was not being considered.

Republicans and Democrats largely backed Obama's decision, seeing it as the next step after congressional passage in 2010 of the Lord's Resistance Army Disarmament and Northern Uganda Recovery Act, which had strong bipartisan support. Congressional outrage over the guerrilla group and Kony also remains strong.

"We are not here to determine whether Joseph Kony is evil," said Rep. Ileana Ros-Lehtinen, R-Fla., chairwoman of the committee. "We know that he is."

Said Rep. Ed Royce, R-Calif.: "Sometimes just getting rid of one person does make a difference." Rep. Donald Payne, D-N.J., talked of a "madman."

Yet lawmakers are weary of war after a decade of fighting in Iraq and Afghanistan, concerned about costs in a time of budget cuts and suspicious of a slippery slope when combat troops are used as military advisers. The long Vietnam War and the disastrous U.S. involvement in Somalia in the 1990s still weigh heavily.

Rep. Donald Manzullo, R-Ill., said there were concerns and anxiousness among lawmakers that the operation could expand, requiring more troops.

Don Yamamoto, deputy assistant secretary of State for African Affairs, said the short-term deployment was part of a larger strategy in partnership with the United Nations, African Union and other partners.

"The protection of civilians continues to be central to that strategy," he said.

Frustration with Obama's use of the military in Libya without congressional approval also concerned some lawmakers, particularly Republicans. However, one of the strongest statements of support came from a conservative GOP senator who didn't attend the hearing but provided a statement.

"This is not a Libya,' said Sen. Jim Inhofe, R-Okla., who later added: "It is time to end Kony's reign of terror."

Attending the hearing was 22-year-old Evelyn Apoko, who was abducted by the Lord's Resistance Army and maimed during years of captivity.