Japan has asked the United States to provide explanations following an incident in which a US fighter jet dumped its two fuel tanks into a lake in northern Japan, amid already-simmering anger at US military-related accidents in Japan.

“We are asking the US side to explain what happened and its cause, and we fully demand the US side take prevention measures,” Japan’s Defense Minister Itsunori Onodera said at a news conference on Tuesday.

The engine of the US F-16 reportedly caught fire shortly after taking off from the Misawa Air Base in Aomori Prefecture in northern Japan early on Tuesday morning.

“The US military has told us that it discarded two exterior tanks on Lake Ogawara just north of Misawa Air Base and landed back at Misawa Air Base,” Onodera said.

The US military said in a statement on Tuesday that an engine fire forced one of its F-16s to “jettison two external fuel tanks into an unpopulated area.”

“The safety of our airmen and our Japanese neighbors is our number one priority during flying operations,” said Colonel R. Scott Jobe, the 35th Fighting Wing commander.

He further said that an investigation will be carried out “to determine the root cause of this incident.”

The accident is the latest in a series of incidents involving US military aircraft, for which US Secretary of Defense James Mattis formerly apologized to Onodera last month.

US military helicopters made at least three emergency landings in the southern Island of Okinawa last month alone.

In December 2017, a 10-year-old boy suffered minor injuries after a window fell from a US CH-53E transport helicopter onto a school sports field on the southern island. In October of the same year, an American military helicopter burst into flames after landing in an empty field on Okinawa.

Public anxiety is already high on Okinawa over the presence of US military personnel.

US forces in Japan have a long history of unruly behavior, which together with the accidents, has prompted the majority of the Japanese population to demand their exit.

Numerous anti-US protests have been held in Japan, particularly in Okinawa, where some 30,000 US military personnel are stationed.