North Korea on Friday said it had tested a new solid-fueled intercontinental ballistic missile (ICBM), which leader Kim Jong Un hailed as a breakthrough in its ability to launch a nuclear counterstrike.

The nuclear-armed North fired what Japan called an “ICBM-class” weapon on Thursday, prompting Japan to issue a rare J-Alert warning for Hokkaido residents to seek immediate shelter. The warning was later rescinded.

Kim, who oversaw Thursday's launch with his young daughter, said the new ICBM, called a Hwasong-18, would "radically promote the effectiveness of its nuclear counterattack posture and bring about a change in the practicality of its offensive military strategy," the North's official Korean Central News Agency reported.