China has invaded Malaysian Airspace, infuriating the Foreign of Ministry.

The Foreign Ministry of Malaysia on Tuesday says it will summon China’s envoy to explain an “intrusion” by 16 People’s Liberation Army Air Force planes.

Malaysia’s air force says in response to the incident it scrambled jets on Monday to conduct visual confirmation after the planes flew within 60 nautical miles of the airspace.

The Chinese planes did not contact air traffic control, despite being asked to several times.

Malaysia describes the incident as a “serious threat to national sovereignty and flight safety.”

The Chinese planes did not contact regional air traffic control despite being instructed several times, the air force said.

Foreign Minister Hishammuddin Hussein revealed Malaysia will now be issuing a note of diplomatic protest and ask China’s ambassador to Malaysia to explain the airspace breach.

“Malaysia’s stand is clear – having friendly diplomatic relations with any countries does not mean that we will compromise on our national security,” Hishammuddin said in a statement.

China’s embassy says the planes conducted routine flight training and “strictly abided by” international law without violating airspace of other countries.