LOS ANGELES — Even after decades of well-documented murder and plunder, even after the International Criminal Court indicted him and President Barack Obama dispatched a special operations team to help catch him, African warlord Joseph Kony remained largely obscure to the West.
That changed with startling swiftness this week, with the viral proliferation of a 29-minute video, ''Kony 2012,'' which calculatedly taps the power of social media in an effort to bring attention to the fugitive leader of the Lord's Resistance Army.
By Thursday, three days after its release on YouTube, the video had been viewed 40 million times, fueled by Tweets from celebrities including Rihanna, Oprah Winfrey and P. Diddy.
"Can I tell you the bad guy's name?" Jason Russell, co-founder of the San Diego-based nonprofit Invisible Children, asks his young son in the video. Russell then shows him Kony's photograph, and explains to viewers that Kony's LRA abducts children for use as sex slaves and child soldiers. Then he inveighs against the possible withdrawal of U.S. troops sent last year to help African troops catch him.
The video's popularity reflects the power of Facebook and Twitter to galvanize a generation moved by vivid, instantly downloadable images and the entreaties of celebrities.
Data collected by YouTube show the video is most popular with boys and girls ages 13 to 17, and young men ages 18 to 24.
No sooner had "Kony 2012'' gone wildly viral than critics on the blogosphere were attacking it for a host of perceived sins, from sentimentality to Western arrogance to dangerous oversimplification.
"The war is much more complex than just one man called Joseph Kony," Ugandan journalist Rosebell Kagumire argued in a YouTube video, describing the Invisible Children video as the work of "an outsider trying to be a hero, rescuing African children."
Ugandan blogger Musa Okwonga wrote that he was stunned to find people tweeting furiously about his country. "All of a sudden, my family's region was famous — or, at least, trending on Twitter. What was all this about?" he wrote in a blog in the Independent.
Invisible Children was founded in 2003 by three California film students moved by their experiences with the victims of war in Africa. It occupies a full floor in a San Diego high-rise where, on Thursday, some 30 college-age workers were answering phones in an office resembling a boiler room. The phones rang persistently with people asking how they could help.
"We're at a place of deep emotion, humility and thankfulness that this is finally catching on," said Lauren Bailey, the movement coordinator.
The massive response to the video has stunned better-known humanitarian groups that have worked for years to draw attention to Kony's atrocities. "We didn't get celebrities going onto Twitter," said Anneke Van Woudenberg, a researcher for Human Rights Watch, which produced its own video on the subject.
"In our video, we tried to get Africans to describe their experiences in their own words. . . . But often, people will pay less attention when an African person tells the story."
Added Adam Rogers, a researcher at the Norman Lear Center at USC: "We could be breeding a culture that thinks hitting the Share button is enough to solve complex social problems. But hitting the Share button is still more than many people were doing beforehand."
Next month, Invisible Children plans a "cover the night" event to dispense T-shirts, bracelets, bumper stickers and buttons in major cities, in part to maintain pressure on Washington to maintain its limited troop presence.
One such event is planned for downtown Tampa on April 20, according to a Facebook page called Stop Kony 2012 Tampa.
The burst of attention has brought scrutiny, including over the ratio of Invisible Children's spending on aid and its rating by the site Charity Navigator.
In a response posted on the Internet, the group said it spends about 80 percent of its funds on programs that further its mission, 16 percent on administration and about 3 percent on fundraising.
Mamood Mamdani, a Columbia University professor who has studied the region, said some Ugandans worry that the video could actually trigger further bloodshed. "We all know that the inevitable result of military activity is that civilians get hurt," he said, cautioning against the influence of "millions of well-meaning and well-intentioned but ill-informed people."
Information from the Associated Press was used in this report.