Pyongyang's move appears to have breathed new life into the six-party talks - which include Russia, North and South Korea, the US, Japan and China.
Russia has suggested restarting the meetings as early as next week.
And President Bush not only pledged to lift some sanctions on the North, but also said he would remove the Stalinist regime from its list of state sponsors of terrorism.
Removal from the terror list would pave the way towards lifting many of the most stringent sanctions.
However, Mr Bush was clear that moves to take the country from the terror list would not begin for 45 days, and would start only if the North's claims were verified.
"We remain deeply concerned about North Korea's human rights abuses, uranium enrichment activities, nuclear testing and proliferation, ballistic missile programmes and the threat it continues to pose to South Korea and its neighbours," he said.
"It will remain one of the most heavily-sanctioned nations in the world."
Lifting the Trading with the Enemy Act has no effect on key restrictions on weapons proliferation, illicit financing activities and money laundering.
And officials said Washington could re-impose sanctions if Pyongyang's declaration failed to live up to expectations.
BBC diplomatic correspondent Jonathan Marcus says the ultimate issue now is what will be done about the small stockpile of highly-enriched nuclear material diplomats believe the North has stashed away.
And the possibility that the country has managed to build a small number of weapons has not even been touched on yet, our correspondent says.
Another potential stumbling block is the allegation that the North helped Syria to build a nuclear facility - a claim denied by Pyongyang.
The next move for North Korea is the destruction of the cooling tower at the Yongbyon reactor. The plant was disabled last year, and the tower's destruction will be televised.
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