US helicopter part crashes on Japanese school in Okinawa

The window dropped on the school grounds, slightly injuring one boy, news agency Kyodo said.

The southern island of Okinawa hosts the largest US military presence in Japan.

Over the past years, a number of accidents and crimes have led to growing local opposition to the US base.

According to the Reuters news agency, Japan's Chief Cabinet Secretary Yoshihide Suga said "this sort of incident creates anxiety not only among those involved with the school but the people of Okinawa and should never happen".

US returns land it's controlled since WWII to Japan amid local anger

But there's a catch.

As part of the Treaty of Mutual Cooperation and Security between the two countries, the United States is granted the right to certain defense facilities. In exchange for the land, the Japanese government built several new helipads for the US military to use on its southernmost island of Okinawa.

Yet the handover has done little to assuage the ire of activists, who've campaigned for decades, to remove US bases altogether from Okinawa.

US Army copter crash-lands on ship off Japan island; 7 hurt

The H-60 helicopter made a hard landing on the USNS Red Cloud cargo vessel around 20 miles (30 kilometers) east of Okinawa, U.S. Forces Japan said in a statement, adding that the cause was under investigation. Okinawa is home to most of the tens of thousands of U.S. troops in Japan.

The injured were transported to a Navy hospital, the statement said. Their conditions were not immediately clear.