North Korean leader Kim Jong-un has expressed hope that friendly ties between North Korea and Vietnam will continue to grow strong in his message to Vietnam's leader To Lam, Pyongyang's state media reported Friday. Kim made the remarks in a reply message sent the previous day to the chief of Vietnam's Communist Party, expressing his thanks to Lam for congratulating him on his reelection as general secretary of the ruling Workers' Party of Korea at last month's party congress, according to the Korean Central News Agency. "Expressing belief that the friendly and cooperative relations between our two parties and two countries will continue to grow strong in the long journey for accomplishing the common socialist cause in the future, too," Kim said in the message. He said Lam's sincere congratulations serve as "active encouragement" to the WPK's struggle for the socialist cause. At the weeklong ninth party congress held in February, Kim was reelected general secretary of the WPK for reinforcing the country's nuclear deterrence under his leadership. In October last year, Kim and Lam held summi