Story highlights Four nations are contributing troops to track down Joseph Kony

The United States is supporting the mission

A video that went viral raised Kony's profile

The notorious warlord is wanted for war crimes

The African Union plans to deploy 5,000 troops to hunt down Joseph Kony, the notorious leader of the Lord's Resistance Army who is wanted for war crimes by the International Criminal Court.

Uganda, the Central African Republic, South Sudan and the Democratic Republic of Congo will supply soldiers for the mission, said Francisco Madeira, the African Union's special envoy on the LRA.

He said the mission has support from the United States and 100 combat-ready troops the Pentagon sent to the region in October will assist.

Kony and the LRA have been terrorizing Uganda and now, neighboring nations, for more than two decades. He is accused of using vicious tactics to recruit children to use them as soldiers and sex slaves and of slicing off ears, noses and limbs of his victims.

There are reports of child soldiers brainwashed into killing their own parents.

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A celebrity-backed video that went viral helped make Kony's alleged crimes more widely known. Invisible Children produced the "KONY 2012" half-hour documentary, viewed more than 84 million times on YouTube.

But in introducing Kony to many for the first time, the video also spurred a flurry of questions about Invisible Children's intentions, its transparency and whether the social-media frenzy was too little, too late.

Kony formed the LRA in an attempt to overthrow the government of Uganda. When that failed and the LRA was pushed out of Uganda in 2006, Kony began moving around in neighboring countries.

Abou Moussa, a special U.N. envoy for central Africa, said there is enough information to believe Kony may be in Central African Republic. It's also believed the LRA soldiers range between 200 and 700 in number.

"I don't think that's the most important thing," Moussa said. "The most important thing is how little they may be, they still constitute a danger to the environment. So they continue to attack, they continue to create havoc."