North Korea launched an unidentified projectile toward the sea on Tuesday, South Korea’s military said.

The projectile was fired off North Korea’s east coast on Tuesday, South Korea’s Defense Ministry said in a brief dispatch.

The ministry gave no further details such as whether the projectile was a missile or an artillery weapon and how far it flew.

Japanese Ministry of Defence said: “North Korea launches a ballistic missile towards the East Sea.”

According to reports, the missiles crashed into the sea after four minutes in the air.

Animosities between the rival Koreas deepened recently after North Korea threatened retaliation after accusing South Korea of flying surveillance drones across the border. The South Korean government denied operating any drones during the times specified by North Korea and began probing if civilians sent them.

Earlier this month, North Korea said it performed test flights of hypersonic missiles. Leader Kim Jong Un observed the launches and underscored the need to bolster the country’s nuclear war deterrent, according to North Korea’s state media.

Tuesday’s launch came ahead of North Korea’s ruling party congress meant to establish new political and economic priorities. The congress would be the first of its kind in five years.