North Korea's state media has confirmed Thursday's launch of two missiles describing them as a "newly developed new-type tactical guided projectile."
State media says the improved weapon system can carry a warhead that weighs 2.5 tons. It claimed the weapon accurately hit a target in waters 600 kilometers east of the Korean Peninsula.
That differs from Japan's estimate, which says the projectiles flew about 450 kilometers.
State media also quoted a senior military official who said the recent launch strengthens the country's military power and deters threats that exist on the Korean peninsula. It remains unclear whether North Korean leader Kim Jong Un was present for the launch.
The move marks the first time the North has fired a ballistic missile in nearly a year and comes just days after it reportedly fired two short-range missiles.
The Japanese government lodged a protest to North Korea through the Japanese Embassy in Beijing.
The Japanese defense minister said the two missiles were a new type of ballistic missile never launched before.
Defense Minister Kishi Nobuo said, "The missiles are believed to have been launched from mobile launchers. This is the same type of system as the one that appeared in a military parade in January. We need to shore up our defense system to ensure safety."
Kishi added that officials of his ministry consulted with their US and South Korean counterparts. They agreed to continue close cooperation.
Earlier on Thursday night, Kishi spoke with British Defence Secretary Ben Wallace by telephone. Kishi and Wallace agreed that the move violated a UN Security Council resolution banning Pyongyang from launching ballistic missiles.
They confirmed that Japan and the UK will work closely for the elimination of all North Korean ballistic missiles in a complete, verifiable and irreversible manner.
During his first formal news conference, US President Joe Biden said Thursday's launch violates the UN Security Council resolution.
Biden said, "We're consulting with our allies and partners and there will be responses, if they choose to escalate, we will respond accordingly."
The Biden administration is in the final stages of reviewing its North Korea policy, which underwent changes under former President Donald Trump.