"Pointing out that the world is rapidly changing and developing, he called for directing steady efforts to putting the factory's overall production process and process for checking goods on a modern basis and introducing update technology, not content with the present success, and thus producing better optical glass and measuring equipment," the KCNA said in an English-language report.

The KCNA added that Kim was accompanied by Choe Ryong-hae, vice chairman of the ruling Workers' Party, and two vice department directors of the party, Jo Yong-won and Kim Yong-su, among others.

This was Kim Jong-un's first visit to Taegwan Glass Factory since May 2014. The plant is also said to have produced military lens, and was subject to South Korea's sanctions in 2016. (Yonhap)