Defense Minister Yasukazu Hamada reported that rescuers were searching for 10 people who may have been on a Japanese helicopter which crashed into the water on Thursday.
Hamada was visibly emotional when he spoke with reporters on Friday.
Gen. Yasunori Morishita is the chief of staff for Japan's Ground Self-Defense Force. He said that searchers have found what appears to be pieces of the UH-60JA in the ocean and continue to scan it for survivors.
According to the Aviation Safety Network, if no survivors were found, this would be the deadliest Japanese military aviation accident in Japan since 1995.
Morishita reported that among the missing soldiers are two pilots and two mechanics as well as six passengers. Among them is Lt. Gen. Yuichi Sakamoto, a senior GSDF Commander.
NHK, Japan's public broadcaster, reported that Sakamoto was appointed as commander of the 8th Division on March 30.
According to the Defense Ministry, the helicopter, which was surveying local areas at the time of the disappearance from radar screens, disappeared Thursday afternoon local time off the coast Miyako Island of the southern Japanese prefecture Okinawa.
Miyako Island is located 400 km (250 miles), east of Taiwan, and houses a JGSDF rocket unit.
A spokesperson for the Japan Coast Guard informed CNN that at 6:50 pm local time, on Thursday evening, a patrol vessel retrieved from the water a lifeboat marked with the words "Ground Self-Defense Force".
A spokesperson said that a window frame and a door bearing the words 'Ground Self-Defense Forces' were found in the early morning hours of Friday north of Irabu Island. Irabu Island is connected to Miyako Island via a bridge.
According to Mitsubishi Heavy Industries, UH-60JA helicopter is a multipurpose helicopter that's based on US Black Hawk helicopters.
According to the Aviation Safety Network, on February 21, 1995 a Maritime Self-Defense Force Flying Boat crashed on Okinawa.
According to the database, on April 26, 1983, eleven people died when a flying-boat crashed during a practice for an airshow in Iwakuni. A week earlier, 14 people had been killed when two Air Self-Defense Force Transports, flying in formation, crashed into an Ise Bay island.