Twelve North Korean female hockey players crossed the heavily fortified border into South Korea on Thursday to form the rivals' first-ever unified Olympic team during next month's Pyeongchang Winter Games.



Fielding the joint hockey team was part of a package of Olympics-related rapprochement deals that the rival Koreas recently struck after a year of heightened regional animosity over the North's advancing nuclear program. Some experts say North may want to use improved ties with South Korea as a way to weaken U.S.-led international sanctions.



On Thursday morning, the North Korean hockey players wearing white and red winter parkas with "DPR Korea," an abbreviation of their country's official name Democratic People's Republic of Korea, written on their backs, arrived in South Korea along with a coach and two support staff. A North Korean advance team tasked with looking at the Olympic stadium and accommodation facilities also came with them, according to Seoul's Unification Ministry.



When busses carrying them left, about 30-40 conservative activists shouted slogans and raised a wood board with a sign demanding the beheading of North Korean leader Kim Jong Un and his photo. It wasn't clear if any of the North Koreans on the buses looked at them.



The North Korean hockey players are to travel on to a southern South Korean training center where they'll be united with their 23 South Korean teammates. They will start their joint practices as early as later Thursday. The North Korean advance team, for its part, moved to eastern towns, where the Feb. 9-25 Olympics are to take place.



The Koreas began exploring how to cooperate in the Olympics after Kim abruptly said during his New Year's Day address that he was willing to send an Olympic delegation. Their rapprochement deals include athletes of the two Koreas marching together under a single flag during the Feb. 9 opening ceremony.



The International Olympic Committee has allowed 22 North Korean athletes, including the 12 hockey players, to compete in Pyeongchang in exceptional entries given to the North, which initially had none to come to the Olympics. The 10 others will compete in figure skating, short track speed skating, Alpine skiing and cross-country skiing, and they will come to South Korea on Feb. 1.



The joint hockey team deal has triggered a backlash in South Korea, with a survey showing about 70 percent of respondents opposing the idea because it would deprive South Korean players of playing time.



Conservatives in Seoul have held a series of small-scale rallies in recent days. On Monday, activists burned Kim's photo and a North Korean flag as the head of the North's popular girl band passed by them during a visit to Seoul. North Korea responded Tuesday by warning similar actions could disrupt ongoing reconciliation efforts.



South Korean officials hope an Olympic-inspired mood of detente would serve as a stepping stone to the resumption of diplomatic talks that could slow down North Korea's nuclear advancement. North Korea, however, has insisted it won't discuss its nuclear program during its ongoing talks with South Korea, and some experts warn that tensions could flare again after the Olympics.