"Dear Mister Chairman..." Bush wrote Kim on December 1, in what the White House described Thursday as his first ever direct communication with the head of a Stalinist regime he once branded part of an "axis of evil."

"He was addressed as 'Dear Mister Chairman,' as he is the chairman of the National Defense Commission of North Korea," spokeswoman Dana Perino told reporters.

"It's on White House letterhead and signed, 'Sincerely,' dated December 1st. The president did hand-sign the letter," said Perino, who indicated that Bush had sent a firm message on the need to meet a December 31 nuclear deadline.

The spokeswoman declined to detail the content, except to quote Bush as telling Kim that the six-country arrangement aimed at ending Pyongyang's nuclear weapons programs stood at a "critical juncture."