POHANG, South Korea, Jumada II 3, 1437, Mar 12, 2016, SPA -- U.S. and South Korean troops staged a big amphibious landing exercise on Saturday, storming simulated North Korean beach defences amid heightened tension and threats by the North to annihilate its enemies, Reuters reported. The landing and assault drills on South Korea's east coast were part of eight weeks of joint exercises between the allies which the South has said are the largest ever. The North has denounced the exercises as "nuclear war moves" and threatened to respond with an all-out offensive. Tension on the Korean peninsula has been high since the North conducted its fourth nuclear test in January and followed that with a long-range rocket launch last month, triggering new U.N. sanctions. About 55 U.S. marine aircraft and 30 U.S. and South Korean ships, including the USS Bonhomme Richard and USS Boxer, which carry AV-8B Harrier attack jets and V-22 Osprey aircrafts, took part in the assault on beaches near Pohang city, the U.S. navy said. The North's military said it was prepared to counter the U.S. and South Korean forces "with an ultra-precision blitzkrieg strike of the Korean style". --SPA 12:27 LOCAL TIME 09:27 GMT www.spa.gov.sa/w