US helicopters in Japan
U.S. military helicopters fly near the Futenma No. 2 Elementary School in Ginowan, Okinawa, on Thursday.
The Japanese government on Friday doubled-down on its accusation that the U.S. Marine Corps flaunted safety concerns by flying helicopters above a school near a U.S. air base in Okinawa, despite U.S. military denials.

"In the video footage (we have), the helicopters' underbellies are clearly visible as they flew," Defense Minister Itsunori Onodera said, referring to video shot from a school which had a helicopter window fall into its grounds on Dec. 13, sparking outrage from the local and central governments.

After the incident, the U.S. Marine Corps in Okinawa had said it instructed all crew of aircraft taking off and landing at the Marine Corps Air Station Futenma to avoid flying over schools to the "greatest extent possible," according to the Defense Ministry.

"Children, teachers and parents will certainly be worried. This is a kind of flight we don't want to see," Onodera said. The minister also said he will continue to urge the U.S. military to avoid flying over the school just outside the Futenma base.

In Okinawa, Gov. Takeshi Onaga expressed strong disappointment over what he sees as a "broken" promise. "It is completely outrageous," he said.

The governor also told a group of Diet members who inspected the Futenma No. 2 Elementary School on Friday that he believes the U.S. forces are "not good neighbors" as they "do not appear to take accidents and crimes (involving their personnel) seriously."

Local concerns are deepening over continuing accidents and mishaps involving U.S. aircraft in the southern Japanese island prefecture, where the bulk of U.S. military forces in Japan are stationed.

The Okinawa prefectural assembly adopted documents demanding the suspension of the Futenma base operations by February next year, and the removal of the Marines from the prefecture, as many of the incident-prone aircraft fly out of the facility.

The Dec. 13 incident also involved a Futenma-stationed CH-53E large transport helicopter. Nobody was injured, but locals were incensed as the window, weighing 7.7 kilograms, landed only meters from where more than 50 children were taking part in physical education activities.

The ministry, for its part, has installed security cameras at the school and sent local defense bureau officials to watch for any U.S. military aircraft flying over.

On Thursday afternoon, cameras and defense officials spotted two AH-1 attack helicopters and one UH-1 multipurpose helicopter flying over the school, according to the ministry, prompting it to lodge an immediate protest.

Responding to questions by media outlets, however, the Marine Corps said in a statement issued the same day that no Marine Corps aircraft were confirmed to have flown over the school based on radar tracking data and pilot interviews.

Onodera told reporters Friday that the ministry has asked the U.S. military to again confirm the circumstances of the flights using video footage shot from its cameras placed at the school.

The ministry said it has not received from the U.S. military its radar tracking data. A ministry official indicated that the ministry has no intention to request U.S. data at the moment.

"We think it is important that the U.S. military, which operates the helicopters, first confirms the situation, as we have passed on the information of what our monitors saw and the video images," Hajime Aoyagi, the ministry's press secretary told a news conference.

No children were in the playground when the three helicopters passed over Thursday, but not long before, students had been evacuated from the area during a drill being carried out in response to the window incident.