It's not common for North Korea to acknowledge military-related setbacks, but observers say the disclosure of the failed ship launch suggests that Kim is serious about his naval advancement program.

North Korea has begun steps to arrest and investigate those responsible for a failed launch of its second naval destroyer this week.

A 5,000-ton North Korean destroyer suffered a "serious accident" during a launch ceremony, state media reported Thursday, with leader Kim Jong Un calling it a "criminal act" and warning of consequences.