July 3 (UPI) -- South Korea fired an army commander, saying the presence of a North Korean fishing boat that sailed in the South's territorial waters for 57 hours was the result of a "border security failure," according to local press reports.
South Korean Defense Minister Jeong Kyeong-doo issued a second apology for the North Korean boat that was carrying four fishermen when it was brought to the attention of authorities, local television network MBC reported Wednesday.
Two of the fishermen returned to North Korea, and another two defected; one crew member reportedly requested to borrow a phone from a South Korean fisherman, so he could speak to his aunt who lives in Seoul.
The incident has brought calls from South Korea's main opposition conservatives for Jeong's resignation. Jeong is not resigning, but acknowledged missteps on Wednesday.
"Our forces were not able to properly monitor or issue an alert," the top South Korean defense official said. "I apologize for this situation and for being unable to [previously] explain the circumstances properly."
An official warning was issued to the chairman of South Korea's joint chiefs of staff, ground operations and naval commanders.
According to government investigation results, it is unclear why the North Korean boat that sailed freely in the South's waters was not reported to authorities.
The boat appeared on ground operations radar for nearly an hour on the evening of June 14, but its appearance went unreported that evening.
Military personnel on duty may have read it as sea clutter -- signals returning from the turbulent ocean surface.
While some officials are being penalized with warnings, others are being dismissed for negligence.
The commander of Seoul's army 8th corps, which supervises the eastern coast, was fired, according to the defense ministry, Yonhap reported Wednesday.
The North Korean boat traveled in the South's waters although it was captured on several video surveillance cameras, according to the report.