SEOUL, South Korea — For as long as Kim Jong-un has been North Korea’s leader, he has called for the simultaneous pursuit of nuclear weapons and economic growth with the aim of making the nation a “great socialist nuclear power.”

On Saturday, however, Mr. Kim abruptly announced he was retiring his signature policy, known as byungjin, or “parallel advance.”

The strategy has been at the center of his government’s propaganda and is enshrined in the charter of the governing Workers’ Party. But Mr. Kim said it was now time to adopt a “new strategic line” and focus the nation’s resources on rebuilding its economy.

As for nuclear weapons, he essentially declared that mission accomplished, saying North Korea no longer needed to test long-range missiles or atomic bombs and would close its only known nuclear test site. The byungjin policy, he said, already had achieved a “great victory” — an arsenal capable of deterring the nation’s enemies.