North Korea fired a series of short-range ballistic missiles on Sunday, according to the South Korean military. Eight rockets were launched from at least four different locations towards the open sea over a period of 35 minutes, the South Korean general staff said. They would have reached a maximum altitude of 25 to 80 kilometers and had flown 110 to 670 kilometers. They would have reached a speed of Mach 3 to 6.

Japanese Defense Minister Nobuo Kishi said none of the missiles fell in Japan’s exclusive economic zone. Japanese Prime Minister Fumio Kishida called for maximum efforts to gather information about the missile launches and ensure the safety of planes and ships. There were initially no reports of damage.

South Korean President Yoon Suk Yeol complained that North Korea has been firing missiles every nine days this year. According to his office, he announced that he would strengthen South Korea’s defense capabilities in alliance with the United States.

On Saturday, the US aircraft carrier Ronald Reagan completed a three-day naval maneuver with South Korea in the Philippine Sea, apparently the first joint exercise involving an aircraft carrier since November 2017. North Korea has long condemned such maneuvers as invasion exercises and has frequently responded by launching missiles.

It was the 18th round of North Korean missile tests this year, including a test of an ICBM. According to experts, the country’s main concern is to modernize its arsenal of weapons and, in view of the fallow nuclear diplomacy, to put pressure on the USA to relax sanctions.