BEIJING, China (CNN) -- Six-nation talks on North Korea's nuclear program resumed Thursday afternoon in Beijing, ending a nine-month hiatus.
Christopher Hill: Need to identify North Korean verification efforts.
The discussions are expected to focus on Pyongyang's recent nuclear declaration that was submitted to China late last month and how to verify the information included in it, which could take months.
"Obviously we are going to focus very much on the verification regime to wrap up this phase," U.S. Assistant Secretary of State Christopher Hill said Thursday, according to the Yonhap news agency of South Korea. "The devil is in the details."
The talks resumed after several perceived positive developments in efforts to dismantle Pyongyang's nuclear program.
North Korea destroyed a water cooling tower in late June at a facility where officials now acknowledge they extracted plutonium to build nuclear weapons.
The destruction of the highly visible symbol of North Korea's long-secret nuclear program came just a day after the country released details of its program.
Some involved in the six-party talks are still taking a wait-and-see approach.
"For now it is too early to say whether it is either optimistic or pessimistic," said Kim Sook, South Korea's chief nuclear envoy.
For months, North Korea has been dismantling other parts of the facility under the watchful eyes of representatives of the six nations that have been involved in the talk.
In addition to the United States and the two Koreas, China, Japan and Russia are taking part in the talks.
On June 26, North Korean officials turned over to China a 60-page declaration, written in English, that details several rounds of plutonium production at the Yongbyon plant dating back to 1986.
In it, North Korea acknowledged producing roughly 40 kilograms of enriched plutonium -- enough for about seven nuclear bombs, according to the U.S. State Department.
In response, U.S. President George Bush said he would lift some U.S. sanctions against North Korea and remove the country from the State Department's list of state sponsors of terrorism.
But he made clear that other sanctions remain in place on North Korea -- which has been on the list since its alleged involvement in the 1987 bombing of a South Korean airliner that killed 115 people.
Other nations are providing food and energy assistance to the secretive nation.
South Korea said Thursday it would ask Japan to join other regional countries in providing aid to the North.
"I will urge Japan to participate in the economic and energy aid in which North Korea is interested," Kim said, according to Yonhap.
North Korea agreed to abandon its atomic weapons program on a promise from the other five nations in the talks that they deliver energy aid equivalent to one million tons of heavy fuel oil.
But Japan has refused to take part, saying Pyongyang must first resolve the issue of Japanese citizens abducted in the 1970s and 1980s.
Tokyo claims 17 Japanese nationals were kidnapped by North Korea. Five have been repatriated and Pyongyang says the rest have died.
North Korea has said it will not move on to the next phase of dismantling its nuclear weapons program before receiving all of the energy aid it has been promised.
To address Japan's concerns, Pyongyang has reopened an investigation into the abduction issue. Tokyo is waiting on the results before deciding whether to provide the aid.