North Korean leader Kim Jong Un and Party General Secretary and State President Nguyen Phu Trong  before a talk during Mr. Kim’s State visit to Vietnam in March, 2019 (Photo: Quang Minh)

Mr. Kim said he believes that “the friendly and cooperative ties between the two parties and countries with a long history and tradition would as ever grow stronger," according to KCNA. In the letter, leader Kim mentioned his first state visit to Vietnam in March, saying it provided an "important occasion" in consolidating and developing relations and friendship between the two countries.