South Korea launched a major live-fire drill near the tense land border with North Korea marking the first anniversary of the sinking of one of its warships. The defence ministry said Tanks, armoured personnel carriers, artillery, helicopters and jets took part in the drill at the Pocheon range, 30 kilometres south of the border. The show of force came a day after the North's military threatened to open fire if a planned launch of leaflets by anti-Pyongyang activists near the disputed Yellow Sea border goes ahead.South Korea is also holding a week-long naval exercise that began on Monday to mark the first anniversary of its warship sinking on March 26 last year. The South accused the North of torpedoing the ship with the loss of 46 lives. Pyongyang denies the charge.