North Korea has fired two ballistic missiles off its east coast, South Korea's Joint Chiefs of Staff (JCS) has confirmed.
Japan also reported an object was fired, and that it may have been a ballistic missile.
Japan's Prime Minister Yoshihide Suga has called the launch "outrageous" saying it threatened peace and security in the region.
This is the second weapons test North Korea has carried out this week.
It is not clear exactly where the missiles were destined for or their flight range, but the JCS said its military was maintaining "a full readiness posture in close cooperation with the US".
Ballistic missile tests contravene UN resolutions designed to curb the North's nuclear activities.
On Monday, North Korea tested a long-range cruise missile capable of hitting much of Japan, calling it "a strategic weapon of great significance".
Experts say the cruise missile could possibly carry a nuclear warhead.
The UN Security Council does not forbid the test of cruise missiles.
But it considers ballistic missiles to be more threatening because they can carry bigger and more powerful payloads, have a much longer range, and can travel faster.
North Korea is facing food shortages and a severe economic crisis - prompting questions about how it is still able to develop weapons.
The country has spent more than a year in isolation. It cut off most trade with its closest ally China to stop the spread of the coronavirus.
China's foreign minister is holding talks with his South Korean counterpart in Seoul on Wednesday.
North Korea's weapons programme and stalled negotiations over denuclearisation are likely to be on the agenda.
In March of this year, Pyongyang defied sanctions and tested ballistic missiles, which triggered a strong rebuke from the US, Japan and South Korea.
And last month the UN atomic agency said North Korea appeared to have restarted a reactor which could produce plutonium for nuclear weapons, calling it a "deeply troubling" development.