In response, President Bush said he will lift key trade sanctions against North Korea and remove it from the U.S. terrorism blacklist, a turnaround in policy toward the communist country he once branded as part of an "axis of evil."
"We will trust you only to the extent you fulfill your promises. I'm pleased with the progress," Mr. Bush said in a statement that he read to reporters in the White House Rose Garden. "I'm under no illusions. This is the first step. This isn't the end of the process. It is the beginning of the process."
President Bush said the move was "a step closer in the right direction" although he made clear the United States remains suspicious about the communist regime in Pyongyang.
"The United States has no illusions about the regime," he said.
Mr. Bush said the United States would erase trade sanctions under the Trading with the Enemy Act, and notify Congress that, in 45 days, it intends to take North Korea off the State Department list of nations that sponsor terrorism.
The president also said the United States would monitor North Korea closely and "if they don't fulfill their promises, more restrictions will be placed on them."
President Bush named North Korea, Iraq and Iran an "axis of evil" after the Sept. 11 attacks, accusing them of state-sponsored terrorism and of seeking weapons of mass destruction.
Along with information about nuclear facilities, North Korea's declaration is to provide a verifiable figure on how much plutonium it has.
Plutonium is the "heart of the game because that is the stuff they make bombs out of," lead U.S. negotiator Christopher Hill told the Associated Press. Hill is involved in the talks under way between Pyongyang and the United States, China, Japan, South Korea and Russia.
North Korea's declaration also won't give a complete accounting of how it allegedly helped Syria build what senior U.S. intelligence officials say was a secret nuclear reactor meant to make plutonium, which can be used to make high-yield nuclear weapons. Israeli jets bombed the structure in the remote eastern desert of Syria in September 2007.
U.S. Secretary of State Condoleezza Rice earlier told reporters in Kyoto, Japan, there was still work to do in verifying that North Korea had given up the pursuit of atomic weapons.
"Any effort to denuclearize the Korean peninsula must contend with the fact that North Korea is the most secretive and opaque regime on the planet," she wrote in an opinion piece published in Thursday's Wall Street Journal. "We will not accept that statement on faith. We will insist on verification."
China has hosted six-country talks that last year secured a deal offering North Korea energy, aid and diplomatic concessions in return for disabling its main nuclear facility and unveiling its past nuclear activities.
North Korea's removal from the U.S. list would ease trade restrictions for the country and open the way for other cooperation with the United States, and eventually enable North Korea to work with the World Bank and other international institutions.