People in Japan turned on their TV sets Tuesday morning to news dominated by J-Alert warnings issued by the government after North Korea launched a ballistic missile over the country for the first time since 2017.

The country's J-Alert warning system was activated at around 7:30 a.m. on Tuesday for Hokkaido, Aomori Prefecture and Tokyo’s Izu and Ogasawara islands.

Under the J-Alert system, developed by the Fire and Disaster Management Agency in 2007, messages are sent in times of national emergencies such as earthquakes, terrorist attacks and certain missile launches.

Warnings are automatically sent to municipalities through satellites and administrative radio networks, and then broadcast to residents through sirens and community FM radios. Smartphone users also get alerts through phone carriers.

“I believe we were able to send the alerts quickly,” the government’s top spokesman, Chief Cabinet Secretary Hirokazu Matsuno, told reporters.

Upon receiving a J-Alert message, people are urged to take shelter either inside buildings or underground, as was the case with Tuesday’s launch. When there’s no building nearby, people are advised to hide behind objects or lie on the ground while protecting their heads. If people are indoors, they are advised to stay away from windows.

The alerts also urge people not to approach debris or objects that may have fallen in the event of a missile strike or overflight.

People in affected areas reacted to Tuesday's missile launch with anger and anxiety.

In Hokkaido, fishing vessels reported no damage to either prefectural port facilities or ships at sea due to falling debris, said Seiji Haraguchi, managing director of the Hokkaido Trawl Fisheries Cooperation.

“But the North Korean missile launch was an extremely dangerous act, and we strongly condemn it,” he said.

A 36-year-old tuna fisher in Oma, Aomori Prefecture, went to check the condition of his boat amid strong rain and wind. "I felt irritated (after hearing the news)," he said. "I really don't want to see any more dangerous acts."

Tadaaki Nagashima, 76, who was on his way to a hospital in the city of Ebetsu, east of Sapporo, expressed frustration after a train he was trying to catch was delayed due to a temporary railway suspension.

"I had never thought a train would be delayed by a missile launch," Nagashima said. "What is North Korea thinking?"

Tuesday's warnings were sent by the Cabinet Secretariat, which keeps watch for potential attacks such as those using ballistic missiles. The Meteorological Agency, meanwhile, issues warnings related to natural disasters such as earthquakes and tsunamis.

In recent years municipalities across the country have conducted drills to prepare for the possibility of a North Korean ballistic missile launch landing nearby. In fiscal 2021, which ended in March, a total of 18 drills were conducted nationwide, according to a Cabinet Secretariat report.

Information from Kyodo added