The statement came after Pyongyang handed over earlier on Thursday detailed data on its nuclear activities to China, breaking a deadlock in the six-nation nuclear disarmament talks.
Bush said the move was "a step closer in the right direction," but added that Washington remained concerned about North Korea's uranium enrichment activities and suspected sales of nuclear technology to other countries.
"The United States has no illusions about the regime in Pyongyang," Bush said at the White House. "If North Korea makes the wrong choices, the United States and our partners in the six-party talks will respond accordingly."
Pyongyang missed a deadline for submitting the data late last year, causing six-nation talks involving China, Japan, Russia, the U.S. and the two Koreas to stall. Pyongyang also agreed in February 2007 to halt its nuclear programs in return for economic aid and diplomatic incentives.
Russia welcomed the steps by North Korea and the U.S.
"We welcome this move, as well as the U.S. pledge to remove North Korea from the list of states sponsoring terrorism and lift sanctions against the country," said Deputy Foreign Minister Alexei Borodavkin, who leads the Russian delegation at the six-party talks.
