South Korea says it scrambled warplanes to intercept a Chinese military aircraft which allegedly entered the South's air defense territory.
The South Korean Joint Chiefs of Staff (JCS) said in a statement on Friday that it sent F-15K fighter jets to intercept a Chinese aircraft – believed to be Y-9 tactical transport plane—that flew into the territory known as the Korea Air Defense Identification Zone (ADIZ) and spent more than four hours there.
It said that the plane was also flying near a submerged rock named Ieodo, which Seoul controls with a research station platform on the top of it.
Seoul later summoned a defense attaché at the Chinese embassy in Seoul and "sternly" urged China to take steps to prevent the incident from recurring.
"Our government expressed our regret and we're taking this extremely seriously," South Korea's Defense Ministry said in a statement.
The ministry claimed that Chinese warplanes had made a similar flight over the South Korean zone in February and April.
In February, Seoul summoned the Chinese ambassador to lodge a complaint, and Beijing said then the aircraft was in a training in line with international law and practice.
As for the new incident, Chinese Foreign Ministry spokesman Geng Shuang told reporters in Beijing Friday he was unaware of the issue and referred questions to China's Defense Ministry.
The Korea Air Defense Identification Zone, which is located near Ieo Island, south of the Korean peninsula, overlaps with the air defense zones designated by China and Japan.
The South extended its own territory in 2013. The zones, however, are classified as international airspace and pilots entering the areas are not legally bound to report their route and purpose to the “host” nation.