Japan and the US began a specific seaborne joint military exercise within the ongoing joint naval exercises that began on Sunday amid heightened tensions with North Korea, media reports said.

The USS Fitzgerald and the Japanese Maritime Self Defence Forces destroyer JMSDF Choukai on Tuesday, participated in the Sea of Japan exercises, involving ships equipped with the Aegis anti-missile system, Efe news cited a statement by the Japanese Self-Defense Forces.
Participating in these exercises, the ships have confirmed their response readiness against any ballistic missile launches by Pyongyang, also rehearsed a data exchange on missile interception and other matters.
USS Fitzgerald homeport during its deployment is the Yokosuka naval base (southeast of Tokyo), while the Chokai is based at the Sasebo naval base, in the Nagasaki prefecture (southeast Japan).
The joint US-Japan military drill took place simultaneously as Pyongyang celebrated the 85th anniversary of the North Korean Army's foundation by conducting large-scale artillery exercises -- in the presence of Kim Jong-un, according to Seoul.

Additionally, a US nuclear submarine has also arrived to the Korean peninsula.
Recent events have worsened the growing tension in the region in the face of persistent weapon tests by North Korea -- the most recent took place early April -- to which the US reacted by dispatching its nuclear aircraft carrier USS Carl Vinson to the Korean peninsula.
This stokes fears that North Korea might be preparing for another nuclear test, given that recent satellite imaging shows activity at the Punggye-ri nuclear testing grounds -- where Pyongyang has carried out its previous nuclear trials.