South Korean soldiers take their positions as a man takes a photo with his iPad during an anti-terror and security drill at a subway station in Seoul April 15, 2013. North Korea celebrated the 101st anniversary of its founder's birth with flowers on Monday, although there was no sign of tension easing as South Korea warned that the North's survival could be in question without change and development. REUTERS/Kim Hong-Ji (SOUTH KOREA - Tags: POLITICS MILITARY)