After Malaysia's military spotted "strange" activity over the South China Sea, the country's foreign ministry announced it will summon China's envoy to explain an "intrusion" by 16 Chinese air force planes into its airspace.
After the planes went within 60 nautical miles (110 kilometers) off the coast of Sarawak, Malaysia's air force scrambled jets on Monday to undertake visual confirmation.
The incident was classified as a "severe threat to national sovereignty and flight safety," according to the report.
Despite being told many times, the Chinese planes failed to contact regional air traffic control, according to the air force.
Malaysia will write a diplomatic protest note and urge China's ambassador to Malaysia to explain the "breach of Malaysian airspace and sovereignty," according to Foreign Minister Hishammuddin Hussein.
In a statement, Hishammuddin said, "Malaysia's position is clear: having amicable diplomatic relations with any country does not mean we will compromise on our national security."
The jets were doing standard flight training, according to China's embassy, and "strictly abided by" international law without breaching other countries' airspace.
According to a spokesman, “China and Malaysia are friendly neighbors, and China is eager to continue bilateral friendly dialogue with Malaysia to jointly preserve regional peace and stability.”
China has been pursuing a broad claim over the South China Sea, which sees roughly $US3 trillion in ship-borne trade pass through each year. It has also constructed military facilities on artificial islands.
Brunei, Malaysia, the Philippines, Taiwan, and Vietnam all claim various islands and features in the area, and China's coastguard often issues warnings to foreign boats and aircraft to leave what it deems its domain.
The planes, which included Ilyushin il-76 and Xian Y-20 strategic transporters, flew in an "in-trail" tactical formation between 23,000 and 27,000 feet, according to Malaysia's air force.
Within Malaysia's exclusive economic zone, a Chinese survey ship and a Malaysian oil exploration vessel had a month-long standoff last year (EEZ).
The Philippines has been protesting for months over the presence of hundreds of Chinese fishing vessels in its exclusive economic zone, which it claims are staffed by militia. The complaints have mainly gone unheeded in China.
