In 1969, North Korea shot down a US EC-121 spy plane over the Sea of Japan, killing all 31 crew on board, which constituted the largest single loss of US aircrew during the Cold War. In 1969, Korean Air Lines YS-11 was hijacked and flown to North Korea. Similarly, in 1970, the hijackers of Japan Airlines Flight 351 were given asylum in North Korea. In response to the Blue House Raid, the South Korean government set up a special unit to assassinate Kim Il-sung, but the mission was aborted in 1972.