Citing a report issued on the Korean Central News Agency, South Korean media reported Pyongyang carried out the twin launches as part of a demonstration for sub-military units to combat enemy targets.
South Korea's Joint Chiefs of Staff reported earlier Tuesday that the pair of launches, which occurred between 7:41 a.m. and 7:51 a.m. local time, saw the missiles fly a distance of about 620 kilometers.
Surfaced photos from the launch appear to show what insiders have described as North Korea's rail-mounted KN-23 missiles.
The Japanese government said there was no information about the fall of North Korean missiles inside the country's exclusive economic zone.
The launch toward the Sea of Japan marked North Korea's fifth launch of 2023, and came just a day after South Korea kicked off its 11-day joint military drills with the US despite repeated protests by Pyongyang.
North Korea earlier relayed to its military forces the need to kick up deterrence measures as a result of the US-South Korea military exercises, which it views as an intent for aggression against Pyongyang and its leadership. The current and looming drills set for later this year are expected to be the largest since the Foal Eagle exercises were held in 2018, under the Trump White House.
Tensions between the US and North Korea have remained prickly since the days of former US President Donald Trump, who on multiple occasions referred to North Korean leader Kim Jong Un as "rocket man" and on occasion issued nuclear threats against Kim. Although relations between the two countries did warm for a brief period under Trump, the eased ties were subsequently trashed after a series of failed negotiations and cold reception by the incoming Biden administration.