The lack of a nuclear or long-range missile test as of Tuesday afternoon led to speculation that Kim Jong-un, the leader of the country, had instead decided to celebrate the anniversary with a large demonstration of conventional weapons.

The South Korean news agency Yonhap, citing an unidentified government source, said the exercise involved 300 to 400 pieces of long-range artillery, of the same type deployed along the border north of Seoul. Seoul, a city of 10 million, lies in range of the North Korean artillery and could experience catastrophic damage if war broke out.

Yonhap called the drill one of the largest live-fire exercises conducted by the North.

South Korea said Monday that it had developed radar that can detect incoming artillery faster and more accurately than the radar it now uses. The Defense Acquisition Program Administration said the technology, to be deployed by 2018, would not enable the South to intercept the rockets but would allow the military to identify their source more efficiently and strike the launchpads.

South Korea remains deeply divided over Thaad, which both Washington and Seoul say is intended to defend South Korea and American troops there from North Korea’s fast-growing nuclear and ballistic missile threats. In Seongju, fierce protests by local villagers and activists arose quickly on Wednesday.

Sirens wailed to alert villagers as a convoy of United States military vehicles carrying the radar, launchpads, interceptor missiles and other key parts of the Thaad system pulled into Seongju.

Hundreds of villagers rushed out, shouting slogans against Thaad and blocking the road. But more than 8,000 South Korean police officers quickly overpowered them, removing the protesters and their cars from the road to let the military vehicles pass on their way to an abandoned golf course, the site of the deployment.

On Tuesday, Beijing sent Wu Dawei, a longtime diplomat handling tensions on the Korean Peninsula, to Tokyo for talks with Japanese Foreign Ministry officials in hopes of warding off military confrontation.