A team of US experts will begin disabling North Korea's nuclear facilities on Monday, a news report said Saturday, marking the biggest step the communist country has ever taken to scale back its atomic program. Top US envoy Christopher Hill said the team would travel Sunday to North Korea's main nuclear complex at Yongbyon, north of the capital, Pyongyang, Kyodo News agency reported. Hill said the group, which arrived in Pyongyang on Thursday, would then start disabling the country's sole functioning reactor there and two other facilities on Monday. The North already shut down the reactor in July, and promised to disable it by year's end in exchange for energy aid and political concessions from other members of talks on its nuclear program: the US, China, Japan, South Korea and Russia. Disabling the reactor would mark a milestone in efforts to convince the North to scale back its nuclear program. The country conducted its first-ever nuclear test in October of last year. The North could still restart the reactor even after disablement, though Hill has said that process would take at least a year. The US and other countries in the nuclear talks demand that Pyongyang completely dismantle its nuclear weapons program.