WASHINGTON (Reuters) - President George W. Bush has urged North Korea to keep its promise to reveal all nuclear programs, in his first direct communication with the reclusive leader of a country he once branded part of an “axis of evil.”

North Korean leader Kim Jong-il in an undated photo released by Korea News Service in Tokyo on June 8, 2007. President Bush has urged North Korea to keep its promise to reveal all nuclear programs, in his first direct communication with the reclusive leader of a country he once branded part of an "axis of evil." REUTERS/Korea News Service/Files

Bush wrote to Kim Jong-il, a communist leader he once said he loathed, telling him “we’re at a critical juncture” for Pyongyang to meet its year-end deadline for key steps toward nuclear disarmament, the White House confirmed on Thursday.

But other U.S. officials acknowledged that North Korea might not fully comply before early 2008 and indicated that Washington was prepared to show some flexibility.

“The president ... stressed the need for North Korea to come forward with a full and complete declaration of their nuclear programs, as called for in the September 2005 six-party agreement,” White House spokesman Gordon Johndroe said.

Visiting U.S. envoy Chris Hill handed the letter to North Korea’s Foreign Minister on Wednesday, Pyongyang’s KCNA news agency said. The White House declined to release a copy.

Bush’s gesture underscored U.S. efforts to get North Korea to make good on its pledge to disable its main nuclear complex and declare all of its nuclear activities in exchange for economic and diplomatic incentives.

White House press secretary Dana Perino said Bush decided to send the letter “so that we can keep it all on track.”

Secretary of State Condoleezza Rice, traveling to Brussels for a NATO meeting, said: “It’s going to take a monumental effort to get all of this done by the end of the year and I am not too concerned about whether it is December 31 or not.”

Bush’s letter signaled limits to U.S. patience but also a willingness to open a new line of communication with the isolated communist state. It was addressed “Dear Mr. Chairman” and signed by the president, Perino said.

Until now, Bush had shunned direct contact with Kim, whom he has called a “tyrant.”

“I loathe Kim Jong-il,” Bush told Washington Post reporter Bob Woodward in an August 2002 interview. “I’ve got a visceral reaction to this guy, because he is starving his people.” In his 2002 State of the Union speech, Bush said North Korea, along with Iran and Iraq, constituted an “axis of evil.”

LETTERS TO ALL SIX PARTIES

In his letter, Bush told Kim that North Korea must not only detail “all nuclear facilities, materials and programs” but address issues of proliferation and uranium enrichment.

Questions about proliferation have increased since an Israeli air strike inside Syrian territory on September 6. Some U.S. officials have linked the raid to suspicions of secret nuclear cooperation between Damascus and North Korea. Damascus and Pyongyang have denied nuclear ties.

While writing to Kim, Bush also sent letters on December 1 to other countries involved in the six-party talks, Russia, Japan, China and South Korea, the White House said.

North Korea shuttered its main reactor at Yongbyon in July under a February deal. In October, North Korea agreed to disable all of its nuclear facilities by the end of this year. In exchange, the impoverished country will receive 1 million tons of heavy fuel oil or equivalent aid.

As part of the accord, Pyongyang, which tested a nuclear device last year in defiance of international warnings, must also provide a complete accounting of its nuclear programs.

Korea expert Noriyuki Suzuki of the Tokyo-based Radiopress news agency suggested the letter was also meant to reinforce some of the potential benefits of compliance for Pyongyang.

“The letter must contain the basic U.S. stance that Washington is ready to drop North Korea from the list of state sponsors of terrorism, improve relations and normalize diplomatic relations ... on condition that the North disable and abandon its nuclear weapons programs,” Suzuki said.

Hill has said the North was moving to cripple the reactor and other units at Yongbyon. But disagreement remains over what should appear in the tell-all declaration.

But Rice took a largely upbeat view, saying, “Things seem to be on track.”