North Korea did not answer calls on a key inter-Korean hotline Tuesday morning hours after launching a ballistic missile over Japanese airspace, only to pick up later in the day, according to South Korea’s unification ministry. 

South and North Korea speak through hotlines twice a day, once in the morning and once in the evening. 

But the two sides failed to connect across one of these lines, hours after North Korea launched a likely intermediate-range ballistic missile (IRBM) over Japan and into the Pacific Ocean.

While initially unclear why North Korea did not pick up the phone, the unification ministry