SEOUL — North Korean leader Kim Jong Un convened top security and foreign affairs officials and ordered them to take ‘‘substantial and high-profile important state measures,’’ state media said Sunday, fueling speculation that he plans to push forward with a threat to explode a nuclear device in defiance of the United Nations.

The meeting of top officials led by Kim underscores Pyongyang’s defiant stance in protest of UN Security Council punishment for a December rocket launch.

Last week, the Security Council condemned North Korea’s Dec. 12 launch of a long-range rocket as a violation of a ban against nuclear and missile activity.

The council, including North Korea ally China, punished Pyongyang with more sanctions and ordered the regime to refrain from a nuclear test — or face ‘‘significant action.’’

North Korea responded by rejecting the resolution and maintaining its right to launch a satellite into orbit as part of a space program.

It warned that it would keep developing rockets and testing nuclear devices to counter what it sees as US hostility.