Envoys from the US and North Korea have expressed optimism after a first day of talks on normalising relations.
US envoy Christopher Hill is seeking reassurance from North Korea
US negotiator Christopher Hill said the two sides had reached a degree of understanding on the way forward.
His North Korean counterpart said he expected a fruitful outcome when the talks in Geneva conclude on Sunday.
They follow a deal promising aid and diplomatic benefits if North Korea disables its nuclear programme. It has already shut down a plutonium reactor.
Speaking after the first day of talks, Mr Hill said the two sides had reached a "substantial understanding", although there was still "a long way to go".
Washington is pressing Pyongyang to declare the full range of its nuclear capabilities, under the terms of the agreement reached in February, and to disable the Yongbyon nuclear reactor it shut down in July.
N Korea to "shut down and seal" Yongbyon reactor, then disable all nuclear facilities
In return, will be given 1m tons of heavy fuel oil
N Korea to invite IAEA back to monitor deal
Under earlier 2005 deal, N Korea agreed to end nuclear programme and return to non-proliferation treaty
N Korea's demand for light water reactor to be discussed at "appropriate time"
For his part, North Korean negotiator Kim Kye-gwan said he expected the meeting would "have a fruitful result".
The BBC's Jonathan Beale in Washington says the Geneva meeting is a sign of progress, but it may take years to achieve the goal of normalising relations.
Observers suggest Washington seems prepared to remove North Korea from its list of countries backing terrorism, but it has yet to make its conditions clear.
North Korea has already shut down its main nuclear reactor at Yongbyon following the deal in February, but it has still not declared all of its nuclear activities.
The Geneva talks this weekend are part of an international talks process involving six nations - the others being Russia, Japan, China and South Korea.
In addition to issues of nuclear disclosure, Japan is refusing to supply energy and aid until a dispute over the abduction of Japanese nationals by North Korean agents during the 1970s and 1980s is resolved.