Seoul said on Saturday it had scrambled military jets to intercept a Chinese aircraft that had entered the South Korea’s air defense territory, Reuters reports. The Chinese aircraft was believed to be a military reconnaissance plane and spent nearly four hours in the Korea Air Defense Identification Zone, the South Korean Joint Chiefs of Staff said in a statement. It would be at least the third such incident this year, and it happened less that two months after Seoul officially lodged a complaint over another incursion. South Korea summoned the Chinese ambassador in February to formally complain. China’s Foreign Ministry said in February the flights were completely in line with international law and practice, adding that “air defense identification zones are not territorial air space.”