SEOUL, South Korea - A North Korean soldier safely defected to the South via the heavily fortified border on Thursday, Seoul officials said, about 40 days after another North Korean soldier fled through a different frontier area amid a barrage of bullets fired by comrades.

North Korean soldiers have occasionally and successfully fled through the land border.

Last month, however, when a North Korean solider crossed the border's jointly controlled area, the only places where rival troops are only feet away, his comrades fired dozens of rounds.

He was shot multiple times and remains hospitalized in South Korea.

On Thursday morning, another soldier, whose personal details weren't immediately disclosed, used a different section of the border to defect and there was no shootout, according to South Korea's Defense Ministry.

Seoul's Joint Chiefs of Staff said North Korea's military hasn't shown any suspicious activities when the soldier arrived at a South Korean frontline guard post.

Spokesman Roh Jae-cheon said the motive for the defection was under investigation.

Thursday's defection increased to four the number of North Korean soldiers to defect via the land border, the Defense Ministry said.

About 30,000 North Koreans have defected to South Korea mostly via China since the end of the 1950-53 Korean War.

Animosities run high on the Korean Peninsula as North Korea has been accelerating its weapons tests as part of its stated goal of achieving a nuclear missile capable of striking anywhere in the United States.

Last month, North Korea test-fired its biggest and most powerful missile in its third intercontinental ballistic missile launch this year.

The Associated Press contributed to this report.