North Korea has fired an 'unidentified ballistic missile', Seoul's military says.
The launch came a day after the U.S. and South Korean militaries began their largest joint field exercises in years on Monday.
South Korea's Joint Chiefs of Staff said the latest launch was made in the morning but did not offer further details, such as how far the missile flew.
A day earlier North Korea said it had test-fired two cruise missiles from a submarine, the first time the country is known to have conducted a launch of that type. Its previous underwater launches all involved ballistic missiles.
It was also the first time North Korea fired multiple missiles from a submarine on a single launch event, observers say.
Pyongyang had vowed a strong response to the U.S.-South Korean drills because it views such military exercises by its rivals as a rehearsal for invasion.
It comes after North Korea's dictator leader Kim Jong-un has called on the military to intensify missile test drills to simulate "real war".
The brute supervised a live-fire artillery drill simulating an attack on a South Korean airfield and called for his troops to be ready to respond to the enemies.
It's an apparent threat to the recent series of military drills between allies the United States and South Korea.
North Korea’s state news agency KCNA said a unit trained for “strike missions” fired a “powerful volley at the targeted waters” and demonstrated its capability to “counter an actual war”.
It continued: “[Kim] stressed that the fire assault sub-units should be strictly prepared for the greatest perfection in carrying out the two strategic missions, that is, first to deter war and second to take the initiative in war, by steadily intensifying various simulated drills for real war."
The United States and South Korea are due to start large-scale joint military exercises known as Freedom Shield.
The US has recently sent long-range B-1B and B-52 bombers for several rounds of joint aerial drills with South Korean warplanes, to counter the growing threat of Kim’s growing nuclear arsenal.
North Korea sees these drills as a provocation and an excuse to practice invasion.
“This is likely only the beginning of a series of provocative tests by North Korea,” Leif-Eric Easley, a professor at Ewha University in Seoul said to Al Jazeera.
“Pyongyang is poised to respond aggressively to major U.S.-South Korea defence exercises, as well as to President Yoon’s upcoming summits with Prime Minister Kishida and President Biden.
"The Kim regime may order missile firings of longer ranges, attempt a spy satellite launch, demonstrate a solid-fuel engine and perhaps even conduct a nuclear test.”