In a little noted change in US nuclear policy, President Barack Obama last week threatened to employ nuclear weapons against North Korea in retaliation for a nuclear attack on South Korea.
Rarely, if ever, has the US disclosed when, under what circumstances or in which country it would use nuclear weapons. Instead, US nuclear doctrine has been wrapped in generalities and ambiguity intended to deter a potential adversary from a nuclear attack by keeping him guessing. Day to day, that doctrine calls for never confirming or denying the presence of US nuclear weapons anywhere.
Last week, however, Mr Obama and his South Korean counterpart Lee Myung-bak issued a joint statement saying that 'the continuing commitment of extended deterrence, including the US nuclear umbrella,' provided an assurance that the US would respond if Pyongyang ever put into action the belligerent rhetoric it has repeatedly hurled at South Korea.
After a meeting in the White House, the two presidents appeared in the Rose Garden where Mr Lee said: 'President Obama reaffirmed this firm commitment to ensuring the security of South Korea through extended deterrence, which includes the nuclear umbrella.' Mr Obama did not mention this commitment during his remarks.
Neither the White House press secretary, Robert Gibbs, nor the White House press corps - being unaware of the nuances of nuclear doctrine - raised the issue of the apparent shift in policy.
Before arriving in Washington, South Korean officials told the South Korean press that Mr Lee would ask Mr Obama for a written guarantee that the US would use nuclear weapons against North Korea in the event of a North Korean nuclear attack.
