South Korea today kicked off a live-fire naval exercise near its disputed sea border with North Korea - a move likely to fan already elevated military tensions with Pyongyang. The three-day exercise in the Yellow Sea is aimed at practising responses to simulated incursions by North Korean vessels and aircraft, the South's navy said in a statement. Also Read:\u00a0Vietnam, South Korea may buy Lockheed planes amid Chinese buildup The manoeuvres will involve 20 naval ships, including an Aegis destroyer, as well as 10 aircraft including anti-submarine helicopters. "If the enemy commits provocative acts again in the Yellow Sea, we are prepared to act swiftly, precisely and sufficiently in order to turn the site of provocation into their own tombs," the navy statement said. The two Koreas fought bloody naval battles near the sea border known as the Northern Limit Line (NLL) in 1999, 2002 and 2009. The North refuses to recognise the NLL, which was drawn unilaterally by the US-led United Nations Command at the end of the 1950-53 Korean War. In 2010, South Korea blamed North Korea for the sinking of one of its warships near the Yellow Sea border, in which 46 sailors died. Live-fire drills in the area invariably spark an angry reaction from the North. Cross-border tensions have been running high ever since North Korea conducted its fourth nuclear test in January and a long-range rocket launch the following month.