North Korea

The highest peak in North Korea is Mount Pektu, a dormant stratovolcano.

An excerpt from the article 24 facts about North Korea

The peak is located in the East Manchurian Mountains on the border between the DPRK and China and is 2744 meters above sea level. At its summit is a volcanic crater in which the water that forms Heavenly Lake floods. The last eruption of the volcano took place in 1903 and so during the Korean Empire.