North Korea fired a missile that landed in the waters between the Korean peninsula and Japan, leading residents of Hokkaido island in Japan to seek refuge.

The Japanese government’s order for residents to take shelter has been lifted since then. Officials retracted an alert after their analysis revealed that there was no reason to be concerned about the island’s safety.

South Korea’s Joint Chiefs of Staffs stated that it had increased its military surveillance in response to the missile launch on Thursday local time. It will remain in close contact with the U.S. as it prepares for any potential follow-up actions by North Korea.

North Korea’s missile launch is the latest in a series of weapons tests conducted this year. It occurred shortly after the country’s leader, Kim Jong-un, pledged to enhance his nuclear capabilities in more “practical and offensive” ways.

North Korea has launched approximately 30 missiles this year in retaliation for joint military exercises carried out by the South Korean and U.S. militaries, which it perceives as preparations for a potential attack. However, South Korean and U.S. officials insist that their drills are purely defensive and are in response to North Korea’s increasing nuclear threats.

There are growing concerns that North Korea could conduct its first nuclear test in over five years. Pyongyang revealed a new type of nuclear warhead in April, but foreign experts are divided over whether it possesses the technology to attach the weapon to its more advanced long-range missiles in a functional capacity.