Lee Jae-myung suffered a wound to his jugular vein and underwent emergency surgery after the attack in January.

The attacker was charged with attempted murder and election law violations after the stabbing, which was carried out before the April 10 parliamentary elections. Prosecutors had sought a 20-year prison sentence.

Police in the southern port city of Busan, where the attack took place, said the assailant wanted to kill Lee, then the leader of the liberal Democratic Party (DP), to prevent him from becoming president.

On Friday, the Busan District Court called the attack “a grave challenge” to the country’s election systems and an act that “significantly destroys social consensus and confidence on the basic liberal democratic principles”, according to the Yonhap news agency.

It cited the verdict as saying the attacker had long loathed Lee because of differences of political opinions, had practised stabbing his neck in advance and followed him on five public events.

The court did not disclose the man’s identity. Police earlier said he is about 67.

The attacker pretended to be a supporter and stabbed Lee in the neck as the politician was surrounded by journalists at an event on January 2. Lee suffered a wound to his jugular vein, underwent emergency surgery and recovered after being hospitalised for about a week.

President Yoon Suk-yeol’s ruling People Power Party (PPP) lost the elections for the National Assembly to the DP and its allies.

Lee last week resigned as party leader and is widely expected to run for the leadership of the DP again at a party convention scheduled for August.

Several high-profile South Korean politicians have been attacked in public. Song Young-gil, who led the DP before Lee, was struck in the head with a blunt object in 2022. And in 2006, Park Geun-hye, who became president in 2013, was attacked with a knife at a rally.