SEOUL, South Korea

IN one of Sun Mu’s best-known paintings from his “Happy Children” series, uniformed North Korean kindergartners sing like birds huddled together on a clothesline, their beaming faces so alike they could be clones. At the bottom of the posterlike image, a red slogan leaps out against a yellow background: “We are all happy children!”

When Sun Mu, an artist from North Korea who uses a pseudonym for security reasons, first exhibited paintings like this in Seoul two years ago, the police showed up to investigate. They had been tipped off by viewers who, missing the intended irony, were upset by what they took to be Communist propaganda — a possible crime under South Korea’s national security laws. After all, rapturously smiling child performers are a familiar feature of North Korean pageants, and the style mimics posters celebrating the North’s authoritarian regime.

“I’m not pro-Communist, far from it,” said Sun Mu, 36, who fled North Korea in 1998 to escape famine and arrived in the South in 2001. “When people look at my paintings, I hope they can hear the children asking, ‘Do you really think we’re happy?’ ”

Sun Mu, who was trained to create posters and murals for the Communist government, is the first defector from the North to have won fame as a painter in the South by applying that same propagandistic style to biting parodies of the North Korean regime.