Japan announced on Tuesday it has canceled a port call in South Korea by its main warship during a multilateral naval exercise. The Defense Ministry said it will not send the helicopter carrier Izumo to Busan in southern South Korea in April, AP reports. The exercise also involves Southeast Asian nations and will be held in waters between South Korea and Singapore. Tokyo plans to participate in the rest of the exercise and hopes that bilateral ties will improve. Relations between the two Asian neighbors have fallen to their lowest level in recent years.