According to Press TV, the missile tracking exercise started on Monday in waters near the Korean Peninsula and Japan, the South Korean Defense Ministry announced in a statement.
The ministry added “During the drill, Aegis warships from each country will simulate detecting and tracking down potential ballistic missiles from the North and sharing information.”
Two US ships are also taking part, with one each from the two Asian countries.
The two-day exercises comes less than two weeks after Pyongyang test-fired a new intercontinental ballistic missile (ICBM), declaring it had achieved nuclear statehood.
Both South Korea and Japan – despite tense relations amid disputes over history and territory – are allies and look to the US for their security.
The latest joint war games are likely to further anger the North, which views such military drills as a rehearsal for war against the country.
In a show of force against Pyongyang, Washington and Seoul staged their biggest-ever joint air drill last week, in a move, the North Korean Foreign Ministry said, made the outbreak of war in the restive region “an established fact.”
North Korea has been hit by multiple sets of UN sanctions over its internationally-condemned ballistic missile and nuclear weapons programs. Pyongyang has however, remained defiant, saying it will continue to develop its military program as a deterrent against potential foreign aggression.
Experts said last month’s test proved the North has mastered the advanced technology needed to allow the rocket to survive re-entry to the Earth’s atmosphere.
This year, North Korea’s young Leader Kim Jong-un and US President Donald Trump have frequently traded threats of war and personal insults.