Alexander Vershbow, assistant defense secretary for international security affairs, before Congress on Tuesday. (Chip Somodevilla — Getty Images)

It’s been a little more than a week since President Obama notified Congress that about 100 U.S. troops, primarily Special Operations Forces, would be deployed to Uganda and neighboring countries to advise local forces in their fight against the LRA, a brutal guerrilla movement that has been carrying out a decades-long campaign against civilians.

On Tuesday, administration officials called before a congressional panel were pressed on exactly how long it would last and what it was aimed at accomplishing.

“This is going to be, you know, an operation that runs in the months, not — not an open-ended operation,” Alexander Vershbow, assistant defense secretary for international security affairs, told members of the House Foreign Affairs Committee. “We will evaluate whether the assistance has achieved its purpose in terms of raising the capacity of our partners, and we may disengage even as they continue the fight on their own.”

The decision to deploy American troops followed the passage of congressional legislation that called on the United States to develop a strategy to help defeat the LRA. Human rights officials have also urged the administration to take stronger action against the group.

But the administration’s deployment of military personnel has drawn a measure of skepticism from lawmakers concerned about the scope of the operation.

U.S. officials have described the mission as an advisory one, saying that American troops would be armed but would engage only in self-defense.

Vershbow and Donald Yamamoto, a principal deputy assistant secretary of state, testified Tuesday that the Americans’ principal goal would be improve the ability of local forces to “fuse” intelligence with operational planning to help capture LRA leader Joseph Kony and his commanders.

Asked how success would be defined, beyond Kony’s capture, Vershbow said officials would look to see whether the U.S. force can help encourage defections from the LRA, reduce attacks by the group’s members and professionalize local forces engaged in the efforts.

The LRA is estimated to have 150 to 200 core fighters. Over the past several years, the group’s members have spread from Uganda to the Democratic Republic of the Congo, the Central African Republic and what is now South Sudan, and have conscripted children, killed and tortured civilians and ravaged villages.

Vershbow, asked for assurances that U.S. troops won’t find themselves entrenched in a conflict in Central Africa, given how long the LRA has survived, said officials have already seen Uganda and other regional militaries achieve success against the guerrillas recently.

“We think we’re building on a fairly strong foundation here,” he said.