Many received the news with disbelief. It was hard to imagine that a lawmaker sitting in the National Assembly was the chieftain of a secret organization that aimed to overthrow the government in an armed uprising. We shuddered with fear and anger.

The court ruling that found Rep. Lee Seok-ki of the United Progressive Party and six others guilty of the charges of treason and praising North Korea proved that those who had even the slightest doubts had been wholly mistaken.

A district court in Suwon on Monday sentenced Lee to 12 years in prison for plotting an armed revolt in support of North Korea. The court said it found Lee guilty of conspiring with members of a clandestine organization to overthrow the South Korean government if a war with North Korea broke out.

It said that in Seoul last May, during secret meetings with about 130 members of the Revolutionary Organization, Lee discussed destroying key infrastructure in South Korea, including oil storage and communication facilities.

“The defendants formed the RO to wait for the right moment to subvert the state while working in various sectors of society, such as the National Assembly, political parties and civic groups,” the ruling said.

The court also found that the RO was the main actor behind the rebellion scheme and Lee was the “man in charge of running it.”

UPP members and other supporters of Lee rejected the ruling, insisting that the judiciary ignored the rule of law in what they call a politically motivated case. What they should be reminded of is that Lee himself said in a hearing on Feb. 3 that he was thankful to the judges for holding the trial in a “fair and objective manner.”

Lee and his group need to do away with their anachronistic affiliation with North Korea. The ruling clearly showed that there are those who maintain blind faith in North Korea’s deadwood socialism and dress it up in the trappings of liberalism or progressivism.

The ruling should provide momentum for the National Assembly Ethics Committee to hasten disciplinary action against Lee. The Constitutional Court also needs to expedite its ruling on the petition to disband the UPP, which won 13 National Assembly seats in the 2012 parliamentary elections.

Weeding out followers of North Korea and wrongheaded socialists from the so-called progressive forces in the country is an urgent task. This is all the more so because another major election is coming up in June.