South Korea urges North to stop \'provocative\' rocket tests

South Korea called Monday for the North to stop its "provocative" rocket tests, after the launch of dozens of rockets in recent weeks -- most recently Sunday -- that Seoul says threaten regional security. North Korea test-fired 25 rockets off its east coast into the Sea of Japan (East Sea) on Sunday -- the latest in a series of launches that have sparked criticism from Seoul and Washington. A spate of missile and rocket tests carried out by Pyongyang between late February and early March were largely seen as a calculated show of force to express its anger at the South's ongoing joint military exercise with the US. "The North should stop actions that cause military tension and unnerve its neighbours," Seoul's defence ministry spokesman told reporters, adding that "provocative action made without any prior notifications... can pose significant danger to sea vessels and aircraft passing by the area." The South's military was closely watching the North's troop movements, said the spokesman, adding there was a possibility of more rocket launches. The rockets were aged versions of Russian-developed Frog rockets, he said, noting the North on Sunday fired "more rockets than normally expected." The US State Department on Sunday called on Pyongyang to refrain from "provocative actions that aggravate tensions." The recent show of force by the North coincided with annual South Korea-US army drills that started in late February and will run until mid-April. The North has habitually slammed the Key Resolve and Foal Eagle exercises -- along with other army drills held south of border -- as rehearsals for an invasion. Seoul and Washington say the exercises are purely defensive. The North's powerful National Defense Commission on Friday went on to threaten to demonstrate its nuclear deterrents in the face of perceived hostility by the US. Seoul's defence ministry said however there was no signs of an imminent nuclear test by the North, which staged three atomic tests in 2006, 2009 and last year.   As the North continues to flex its military muscles, its leader Kim Jong-Un guided a flight exercise by air force, state-run news agency KCNA said Monday. During the drill of the Korean People's Army air and anti-air force unit 188, the airmen vowed to bring down "robber-like US imperialists" when ordered by Kim, it said. Kim praised their battle-readiness in the spirit of becoming "human bombs," it said.