SEOUL North Korea on Tuesday showed detailed photos of Kim Jong Un directing rocket launches from a site close to the South in an apparent act of defiance that puts a personal face of its leader to actions provoking its neighbours.
Satellite imagery and photos released by state media show the rockets were fired several kilometers north of a popular South Korean tourist observatory near the inter-Korean Demilitarised Zone (DMZ).
The roar of rockets and the burning trails from the Soviet-era projectiles on Monday could be seen rising from clouds of smoke between mountains on the North Korean side, footage filmed by staff members at the observatory and obtained by Reuters showed.
It was not immediately clear why North Korea conducted drills so close to the border, but state media has in recent days called the presence of a U.S. Navy aircraft carrier in South Korea a "sinister interference."
The United States, which has more than 28,000 troops stationed in South Korea, said it was concerned by reports of recent North Korean missile launches.
U.S. State Department spokeswoman Jen Psaki said it was "not appropriate" to try to link the launches to joint military exercises between the United States and South Korea.
"These annual joint exercises are transparent, defense-oriented. They've been ... carried out regularly and openly for roughly 40 years now. And these recent missile launches were conducted without warning and are clearly designed to raise tensions," Psaki told a regular news briefing.
North Korea routinely fires short-range missiles or rockets into waters off its east and west coasts, but state media rarely shows Kim supervising drills so close to South Korea and has only in recent weeks shown the young leader present at short-range ballistic missile and rocket launches.
Kim personally gave the order to launch the rocket barrage, the North's main newspaper, the Rodong Sinmun, suggesting his growing confidence in actions that infuriate the South and neighboring Japan. South Korean officials confirmed the reports.
"North Korea fired from a position very close to the DMZ. It represents such a threat to South Korea that even our civilian tourists were able to witness columns of water caused by North Korean shells landing in the sea," South Korean Defence Ministry spokesman Kim Min-seok said at a news briefing.
"Our government takes the firm stance that we will mercilessly retaliate if North Korea fires missiles or artillery south of its border with the DMZ."
Photos carried by North's main newspaper showed mobile rocket launchers firing projectiles beside an inter-Korean railway that heads into a mountain range which North Korea has declared a special tourism zone and was once open to South Korean tourists.
North and South Korea are still technically at war after the 1950-53 Korean War ended in a truce, not a peace treaty. The rivals are scheduled to meet this Thursday to discuss preparations ahead of the Asian Games, due to be held in the South Korean city of Incheon later this year.
Last Sunday, state media showed Kim supervising the launch of two Scud-class missiles, in defiance of a United Nations ban on the isolated country's use of ballistic missile technology.
North Korea, whose lone major ally is neighboring China, has threatened a fourth nuclear test in violation of U.N. sanctions and has test-fired short-range missiles and rockets four times in the past two weeks.
(Addition reporting by Ju-min Park in SEOUL and David Brunnstrom in WASHINGTON; editing by Nick Macfie and G Crosse)