A North Korean artillery launch happened minutes before a Chinese commercial plane reportedly carrying 202 people flew in the same area, South Korean officials said.
It was not immediately clear what danger, if any, the launch on Tuesday posed to the China Southern Airlines plane travelling from Tokyo to Shenyang, China.
But Seoul defence ministry spokesman Kim Min-seok called it a “serious threat” that Pyongyang failed to notify international aviation authorities of its launch plans in the area.
He said the plane was travelling at an altitude of six miles, while the projectile’s peak altitude was 12 miles. He said the flight passed through the area about five minutes after the projectile hit the water.
A North Korean army spokesman said last night that rocket drills conducted from February 21 until Tuesday were part of regular training.
He said neither regional security nor the international navigation were in danger because the North took “scrupulous advance security measures for flight orbit and targets in the designated waters”.
A Chinese foreign ministry spokesman called for all sides to continue improving relations and to refrain from provocations.
Seoul officials say the suspected artillery launch on Tuesday and others that included Scud missiles in previous days were protests of ongoing US-South Korean military drills that Pyongyang considers invasion preparation.
Washington and Seoul say the drills, which prompted threats of nuclear war from the North a year ago, are defensive in nature and meant to deter North Korean aggression.
It was not immediately clear what kind of artillery the North launched. But South Korean officials believe the recent series of launches were in part an effort to test 300-mm multiple rocket launchers.
If fired from near the demilitarised zone separating the rival Koreas, such rockets could reach the headquarters of the South Korean army, navy and air force.
Despite the recent firings and launches, outside analysts say the North is taking a softer stance toward the US-South Korean military drills this year than last year because it wants better ties with the outside world to revive its struggling economy.
Also today, Seoul said that North Korea rejected Seoul’s proposal to hold talks on reunions of families divided by the 1950-53 Korean War.
South Korea wants to make such reunions, which were held last month for the first time in more than three years, regular events, but analysts say Pyongyang worries that could take away a key piece of political leverage with the South.
The Korean Peninsula remains officially at war because the Korean War ended with an armistice, not a peace treaty.
Tension spiked sharply a year ago as North Korea responded furiously to last year’s drills and to international condemnation of its third nuclear test in February 2013.