WASHINGTON (REUTERS) - The United States formally complained to China after Chinese nationals pointed lasers at US military aircraft near Djibouti in a number of incidents in recent weeks, the Pentagon said on Thursday (May 3).

The US military has been grappling with lasers being pointed at aircraft for decades. However, the incidents highlight the concern the United States has about a Chinese military base just miles from a critical US base in Djibouti.

"They are very serious incidents... We have formally demarched the Chinese government and we've requested the Chinese investigate these incidents," Pentagon spokeswoman Dana White told reporters.

White said the Pentagon was confident that the lasers had been pointed by Chinese nationals and in the past few weeks fewer than 10 incidents had taken place.

The intent was unclear.

A US official, speaking on the condition of anonymity, said that in one incident last month two pilots in a C-130 suffered minor eye injuries.

The official said that in a few instances, military grade lasers from the Chinese base had been pointed at aircraft.

Djibouti is strategically located at the southern entrance to the Red Sea on the route to the Suez Canal.

Djibouti hosts a US military base that is home to about 4,000 personnel, including special operations forces, and is a launch pad for operations in Yemen and Somalia.

This year, the US military put countering China, along with Russia, at the centre of a new national defense strategy.