North Korean leader Kim Jong Un has opened a rare ruling party congress — only the second since the strongman came to power — with an admission that the economic strategy he unveiled at the previous meeting had not panned out, state media reported Wednesday.

"The five-year economic development strategy period wrapped up last year, but the results in most areas fell extremely short of our goals," the ruling party’s Rodong Sinmun daily quoted Kim as saying in his opening speech a day earlier.

Kim also said he would reveal "the key line of struggle and strategic and tactical policies" for "the cause of national reunification, promoting external relations and strengthening the work of the Party" during the congress, state-run Korean Central News Agency said.