SEOUL, South Korea (AP) — Once or twice a year, activity on the streets of South Korea's capital freezes as a wailing siren marks a nationwide drill aimed at preparing against a North Korean attack. Cars stop on roads. Pedestrians move into buildings and subway stations. Government buildings are evacuated.

The scenes during the latest air-raid drill on Wednesday are remarkable for turning parts of this usually bustling city into a ghost town. But a closer look raises questions about whether the exercises are adequately preparing South Koreans while the threat from North Korea's nuclear and missile program grows.

For many, there's no real training, just people standing around in schoolyards or other gathering spots, staring into their smartphones, chatting amiably or just looking bored or frustrated.

Many schools don't participate in the air-raid drills and those that do often escort children outside. Leaving their buildings would be a good idea during earthquakes, but a terrible decision during attacks.

The country has nearly 19,000 evacuation shelters, mostly built in subway stations and the parking garages of apartments and large buildings. Yet a 2014 government survey found that an overwhelming number of South Koreans did not know which shelters were closest to their homes.

"No, I don't know. I don't think anybody knows," 31-year-old Park Ji-na said shortly after Wednesday's drill.

The 2014 survey, by the National Disaster Management Research Institute, also found that only 10 percent of the 145 adults polled had CPR experience, and just 7 percent owned gas masks.

Most South Koreans have lived their entire lives facing threats from North Korea, and few show great worry.

"Realistically, the people who live in this country aren't thinking much about" the threats, Park said. "They are on the news all the time, but it's not like they are real threats affecting our lives."

National and local governments and even companies organize the exercises. South Korea launched its current civil defense program in 1975, when the country was still run by a military dictator. Before that, nationwide evacuation drills were held on the 15th of nearly every month.

In decades past, civil servants wearing yellow armbands whistled people off the streets and teachers ordered school children to crouch under their desks for exercises that lasted 30 minutes. There were even nighttime drills where people were instructed to turn off the lights and televisions at their homes to deter an imaginary attack by North Korean bombers.

The drills became less frequent and more casual after the 1990s amid rising public complaints and a temporary improvement in relations between the rival Koreas. Today, though North Korea's nuclear weapons development and fierce rhetoric have drawn deep international concern, South Koreans are both inured to the threats and distracted by life in a country that is now about Asia's busiest and most vibrant.

Kim Dae Young, a military expert at the Korea Research Institute for National Strategy, said the drills are failing to equip people with even basic information, such as how and where to evacuate and how to secure drinking water and other supplies during times of crisis.

Noh Sang-yeol also was among those who did not know the shelter closest to his home. The 65-year-old said there's a need to strengthen training programs because the current drills are doing "nothing at all" to prepare people.

"I read from the newspapers that people in Japan, Guam or Taiwan are preparing well and even stacking up on food in case of emergency, and that made me think whether I should begin buying water or batter supplies," he said.

Wednesday's air-raid drill followed North Korea's two intercontinental ballistic missile tests in July and its threat to lob missiles toward Guam earlier this month. The government had planned to send military planes over major cities emitting colored smoke to simulate an attack, but the flights were canceled in Seoul and many other areas due to heavy rain and low clouds, according to the Seoul's Ministry of Interior and Safety.

Government workers during the drill distributed leaflets instructing people what to do during an attack, which included recommendations to prepare to gas masks, raincoats and soap in case of nuclear, biological or chemical attacks. It also reminded people to evacuate to the higher floors of buildings, instead of subway stations or parking garages, in case of chemical attacks.

The civil defense drill coincided with a large-scale joint military exercise between Washington and Seoul that runs through Aug. 31. This annual exercise has predictably drawn a verbal outburst from Pyongyang, which claims the war games are an invasion rehearsal.

The lax civilian drills bother experts, who say stronger training is crucial, especially for the 25 million living in Seoul and its neighboring metropolitan areas. They would only have minutes to respond to incoming North Korean missiles or artillery shells.

The practices of the 1970s and 80s won't return, but experts say the drills should at least focus on giving people practical skills in rescue and evacuation.

Even the South's emergency infrastructure is lacking, said Kim, the military expert. Aside from a few facilities in small border islands that have occasionally seen military skirmishes between the Koreas, South Korea's civilian shelters are not equipped to handle attacks involving nuclear, chemical or biological weapons, Kim said.

"The government should start building bunkers that could withstand nuclear attacks in Seoul and the neighboring metropolitan area," Kim said. "Civil defense needs to become a more important part of the national defense strategy as North Korean threats grow."